invited speakers: 1-4 abstracts - elena...

BOOKOFABSTRACTS

RSCTHEORETICALCHEMISTRYGROUPCONFERENCEUniversityofNottingham,June20-22,2016

InvitedSpeakers:1-4ContributedTalks:5-15TCGGraduateStudentMeeting:16-25Posters:26-43

1

InvitedSpeaker

InvitedSpeakersHigh-dimensionalquantumdynamicsoffunctionalorganicpolymermaterials:coherenceandcorrelationsatthenanoscale……….2IreneBurghardt(GoetheUniversityFrankfurt)

TaylorseriesexpansionsoftheKohn-ShampotentialNikitasGidopoulos(DurhamUniversity)

Exploringtheactivationmechanismsinligand-gatedionchannelsbyenhancedsamplingmethods……….3CarlaMolteni(King'sCollegeLondon)EvolutionthroughcooperativityinthealkalinephosphatasesuperfamilyLynnKamerlin(UppsalaUniversity)PropertiesandspectraofionicandmolecularliquidsEvaPerlt(UniversityofBonn)Simulatingexcited-statesdynamicsusingtheMCTDHmethod……….4GrahamWorth(UniversityofBirmingham)

2

InvitedSpeaker

High-dimensionalquantumdynamicsoffunctionalorganicpolymermaterials:Coherenceandcorrelationsatthenanoscale

IreneBurghardt1,MatthiasPolkehn1,RobertBinder1andHiroyukiTamura2

1InstituteforPhysicalandTheoreticalChemistry,GoetheUniversityFrankfurt,60438FrankfurtamMain,Germany2WPI-AdvancedInstituteforMaterialResearch,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai980-8577,

JapanWepresenthigh-dimensional quantumdynamical studiesofultrafastphotoinducedexciton

migrationanddissociationinfunctionalorganicmaterials,inviewofunderstandingtheintricateinterplayofelectronicdelocalization,coherentnonadiabaticdynamics,andtrappingphenomena.Ashighlightedbyrecentexperiments,quantumcoherencecanplayakeyroleintheelementarytransfersteps,despitethepresenceofstaticanddynamicdisorder.Ourapproachcombinesfirst-principlesparametrizedHamiltonians,basedonTDDFTand/orhigh-levelelectronic structure calculations, with accurate quantum dynamics simulations using the Multi-ConfigurationTime-DependentHartree(MCTDH)method[1]anditsmulti-layerandGaussian-based[2]variants,andaswellasnon-Markovianreduceddynamicstechniques[3].Thistalkwillspecificallyaddress(i)excitondissociationand freecarriergeneration indonor-acceptormaterials, includingmodels forP3HT-PCBMheterojunctions[4,5]andhighlyorderedthiophene-perylenediimideassemblies[6,7],(ii)excitonmultiplicationinacenematerials[8],and(iii)theelementarymechanismofexcitonmigrationaswell as charge-transfer exciton formation in polythiophene and poly-(p-phenylene vinylene) typematerials[9].Specialemphasisisplacedonthespecificinfluenceofmolecularpacking,whichcanactasdeterminingfactorinefficientenergyandchargetransfer.Thepresentedcasestudiesillustratethatthehierarchicalmulticonfigurationalapproachisideallytailoredtovibroniclatticemodelsinmanydimensions.Againstthebackgroundofthesestudies,wewillcommentontheroleoftemporalandspatialcoherence,alongwithaconsistentdescriptionofthetransitiontoaclassicalstatisticalregime.[1]M.H.Beck,A.Jäckle,G.A.Worth,H.-D.Meyer,Phys.Rep.324,1(2000).[2]G.W.Richings,I.Polyak,K.E.Spinlove,G.A.Worth,I.Burghardt,B.Lasorne,Int.Rev.Phys.Chem.,34,265(2015).[3]K.H.Hughes,B.Cahier,R.Martinazzo,H.Tamura,I.Burghardt,Chem.Phys.442,111(2014).[4]H.Tamura,I.Burghardt,J.Am.Chem.Soc.135,16364(2013).[5]M.Huix-Rotllant,H.Tamura,I.Burghardt,J.Phys.Chem.Lett.6,1702(2015).[6]M.Polkehn,H.Tamura,P.Eisenbrandt,S.Haacke,S.Méry,I.Burghardt,J.Phys.Chem.Lett,7,1327(2016).[7]L.Li,P.Eisenbrandt,T.Roland,M.Polkehn,P.-O.Schwartzetal.,Phys.Chem.Chem.Phys.DOI:10.1039/C6CP00644B(2016).[8]H.Tamura,M.Huix-Rotllant,I.Burghardt,Y.Olivier,D.Beljonne,Phys.Rev.Lett.,115,107401(2015).[9]J.Wahl,R.Binder,I.Burghardt,Comput.Theor.Chem.,1040,167(2014).

3

InvitedSpeaker

Exploringtheactivationmechanismsinligand-gatedionchannelsbyenhancedsamplingmethods

CarlaMolteni

King'sCollegeLondon,London,WC2R2LS,UK

E-mail:[email protected]

Pentamericligand-gatedionchannels(pLGICs),embeddedinthemembraneofnervecells,areimportantneuroreceptorsthatmediatefastsynaptictransmission,areinvolvedinseveralneurologicaldisordersandaretargetsitesfordrugsand,ininvertebrates,insecticides.However,wehavelittleideaofhowtheyfunctionatthemolecularlevelduetotheircomplexityandlimitedexperimentalinformation.Wehaveinvestigatedthefirstcrucialstepoftheiractivationmechanism,whichconsistsinthebindingofa neurotransmitter to their extracellular domain, focussing of the prototypical case of theneurotransmitterGABAbinding to the insectRDL receptor,which is linked to the resistance to theinsecticide dieldrin. Using the ``funnel-metadynamics'' computational technique, which efficientlyenhancesthesamplingofboundandunboundstatesusingafunnel-shapedrestrainingpotentialtolimittheexplorationinthesolvent,wehavedescribedthebindingfreeenergylandscape,identifiedthechainofevents leadingGABAfromthesolvent intothebinding-pocketandestimatedthebindingaffinity.Moreover,wehaveshownhowthislandscapeisdisruptedbymutationswhichpreventthereceptortofunction.Wehavealsoassessedthepotentialoftrans-cisprolineswitchforthegatingoftheionchannel,inthecaseofthe5-HT3receptor,whichisactivatedbyserotonin.TheRDLandthe5-HT3receptorssharestructuralandfunctionalfeatureswithotherpLGICs,henceourworkprovidesvaluableprotocolstostudytheactivationmechanismsofpLGICsbeyondconventionaldockingandmoleculardynamicstechniques.

4

InvitedSpeaker

Simulatingexcited-statesdynamicsusingtheMCTDHmethod

GrahamWorth

SchoolofChemistry,UniversityofBirmingham,Edgbaston,B152TT,UKE-mail:[email protected]

To study the time-evolution of photo-excited molecules it is necessary to solve the time-

dependent Schrödinger equation. Theeasiestway todo this conceptually is toexpand thenuclearwavefunctioninabasissetandsolvetheresultingequationsofmotion.Themulti-configurationaltime-dependentHartree(MCTDH)methodisanefficientwaytodothis[1,2]andhasbeenusedinthestudyofavarietyoffundamentalprocesse.Recentcalculationshavebeenusedto,e.g.unravelthesignaloftime-resolvedphoto-electronspectroscopyofpyrrole[3]and identifyanewchargetransferstate inpyrroleclusters[4].Muchoftheeffortforsuchcalculationgoesintocalculatingthepotentialenergysurfaces. In the talk, recent developments of the direct dynamics variational multi-configurationalGaussian(DD-vMCG)method[5,6]willbepresented.Inthesecalculationsthepotentialenergysurfacesarecalculatedon-the-fly,makingthemmorestraightforwardtorun,onlylimitedbytheaccuracyofthequantumchemistrymethodused.

[1]M.Beck,A.Jackle,G.A.Worth,andH.-D.Meyer,Phys.Rep.,2000,324:1–106.[2]G.A.Worth,H.-D.Meyer,H.Koppel,L.S.Cederbaum,andI.Burghardt.Int.Rev.Phys.Chem.,2008,7:569–606.[3]G.Wu,S.P.Neville,O.Schalk,T.Sekikawa,M.N.R.Ashfold,G.A.Worth,andA.Stolow.J.Chem.Phys.,2015,142:074302.[4]S.P.Neville,O.Kirkby,N.Kaltsoyannis,G.A.Worth,andH.H.F.Fielding.NatureComm.,2016,7:11357.[5]G.W.Richings,I.Polyak,K.E.Spinlove,G.A.Worth,I.Burghardt,andB.Lasorne.Int.Rev.Phys.Chem.,2015,34:269–308.

5

ContributedTalk

ContributedTalksSelf-consistentimplementationofmeta-GGAexchange-correlationfunctionalswithintheONETEPlinear-scalingDFTcode……….6JamesC.Womack(UniversityofSouthampton)DFT-basedembeddingmethods……….7FredManby(UniversityofBristol)Artificialnucleicacids:Coupledclustersolvatedelectronicspectroscopyto50µsMDsimulationofAEGIShelices……….8RobertMolt(CardiffUniversity)FasttimedependentDensityFunctionalTheorycalculationsofX-rayabsorptionandemissionspectroscopy……….9NickBesley(UniversityofNottingham)Moleculardynamicsstudyofself-assemblyofaqueoussolutionsofpoly[9,9-bis(4-sulfonylbutoxyphenylphenyl)fluorene-2,7-diyl-2,2’-bithiophene](PBS-PF2T)inthepresenceofpentaethyleneglycolmonododecylether(C12E5)……….10BeverlyStewart(UniversityofCoimbra)Correlationconsistentbasissetsforthegroup1atomsK-Fr……….12GrantHill(UniversityofSheffield)RadicalSAMenzymes-Mechanism,dynamicsandradicalreactionprofiling……….13ChristofM.Jaeger(UniversityofNottingham)Oscillatingchargemigrationbetweenglycinelonepairssilencedbynucleardelocalisation:CASSCFEhrenfestdynamicsstudy……….14IakovPolyak(ImperialCollegeLondon)UranylU-Oylstretchingvibrationsasaquantitativemeasureofequatorialbondcovalency:aquantumchemicalinvestigation……….15AndyKerridge(LancasterUniversity)

6

ContributedTalk

Self-consistentimplementationofmeta-GGAexchange-correlationfunctionalswithintheONETEPlinear-scalingDFTcode

JamesC.WomackandChris-KritonSkylaris

Chemistry,FacultyofNatural&EnvironmentalSciences,

UniversityofSouthampton,Highfield,Southampton,SO171BJ,UKE-mail:[email protected]

IntheKohn-Shamformulationofdensityfunctionaltheory(DFT),thecomplicatedexchangeand

correlationinteractionsofmany-electronsystemsaredescribedbytheexchange-correlationfunctional,Exc[n],forwhichtheexactformisunknown.Numerousapproximateformsforthisfunctionalhavebeendevelopedoverthepastseveraldecades,andarecategorizedintobroadfamiliesbythecharge-density-dependentingredientsusedintheirconstruction.WhiletheLDA(localdensityapproximation)andGGA(generalizedgradientapproximation)familiesusethechargedensity,n,and itsgradient,todescribeexchangeandcorrelationeffects,functionalsfromthemeta-GGAfamilytypicallyalsodependuponthekineticenergydensity,τ.Theuseofτtoconstructexchange-correlationfunctionsallowsthedevelopmentofmoresophisticated, flexibleandaccurate functional forms,butalsopresentsnewchallengesandcomplexitiesfortheirimplementation.Inordertoextendthetheoreticaladvantagesofmeta-GGAfunctionalstolarge-scaleDFTcalculationsonthousandsofatoms,wehaveimplementedsupportforτ-dependentmeta-GGAfunctionalsinONETEP[1],alinear-scalingelectronicstructurepackage.TheONETEPcodeachieveslinear-scalingcomputationalcostwithnear-complete-basis-setaccuracybymeansofauniqueformulationofdensity-matrixDFTinwhichthetotalenergyisdirectlyminimizedwithrespecttoboththedensitymatrixandasetofstrictlylocalized,self-consistentlyoptimized localorbitals (non-orthogonalgeneralizedWannier functions,orNGWFs).The self-consistent implementation of meta-GGA functionals within the linear-scaling formalism ofONETEP presented some significant challenges, requiring detailed consideration of the effect of τ-dependenceonthegradientofthetotalelectronicenergy,andtheformoftheτ-dependentexchange-correlationpotentialintermsoftheNGWFsusedinONETEP.Inthiswork,wepresentthetheoreticalinnovationsnecessarytoimplementτ-dependentmeta-GGAfunctionalsforuseinself-consistentlinear-scalingDFTcalculationsusingONETEP.Wealsopresentthevalidationoftheaccuracyoftheimplementedmeta-GGAfunctionalsanddemonstratethecomputationalscalingofourapproach.[1]C.-K.Skylaris,P.D.Haynes,A.A.Mostofi,andM.C.Payne,J.Chem.Phys.,2005,122,084119.

7

ContributedTalk

DFT-basedembeddingmethods

FredManby

BristolUniversitySchoolofChemistry,EnglandE-mail:[email protected]

Variousquantumembeddingtechniques,inwhichonequantummechanicalleveloftheoryis

embedded in another, are emerging as powerful tools for extending thedomainof applications inquantumchemistry.InthistalkIwillsurveysomeofthekeydevelopments,anddescribevariouseffortsin our own group to developmethods that allow embedding of high-accuracy electronic structuremethods in density functional theory, and extension of quantum chemistry to condensed-phaseproblems.

8

ContributedTalk

Artificialnucleicacids:Coupledclustersolvatedelectronicspectroscopyto50μsMDsimulationofAEGIShelices

RobertMolta,b,JasonByrdc,MillieGeorgiadisd,andNigelRichardsa

aSchoolofChemistry,CardiffUniversity,ParkPlace,Cardiff,CF104AT,UK

bDepartmentofChemistryandChemicalBiology,IndianaUniversity-PurdueUniversityIndianapolis,IN,46202,USAcDepartmentofChemistry,QuantumTheoryProject,UniversityofFlorida,GainesvilleFL32611,USA

dDepartmentofBiochemistry&MolecularBiology,IndianaUniversitySchoolofMedicine,Indianapolis,IN,46202,USA


We present the physical chemistry underlying several artificial nucleic acids from ab initiofragmentcoupledclustercalculationsto50μsMDcalculationsofAEGISDNAhelices.Artificialnucleicacidshavebeenexpandinginutility,capableofformingstableDNAhelicesexperimentally,andrepresentapromisinghorizonoffuturegeneticmanipulation.Ourstudiesrangefromestablishingthepropertiesofindividual nucleic acids, quantifying the dispersion of their stacking interactions, establishing thetautomericequilibriaviacalculatedelectronicspectroscopyinsolution,andobservingthemacroscopicDNAhelicaleffectsoftheunusualdispersioninteractionsofartificialnucleicacids.Thisworkservestoadvancefragmentedcoupledclustermethodologyaswellasgiveinsighttothechemistrygoverningsyntheticbiology.

9

ContributedTalk

Fasttime-dependentDensityFunctionalTheorycalculationsofX-rayabsorptionandemissionspectroscopy

NicholasA.Besley

SchoolofChemistry,UniversityofNottingham,UniversityPark,Nottingham,NG72RD,UK


AdvancesinexperimentaltechniqueshaveprovidedX-rayspectroscopywithamuchgreaterrichnessinstructureandtheabilitytoprobechemicalprocessesonanultrafasttimescale.Quantumchemicalcalculationsoftenplayakeyroleintheanalysisofexperimentaldataanditisimportantthatthecomputational methodology progresses alongside experiment. In this talk the calculation of X-rayabsorptionandemissionspectroscopyusingtime-dependentdensityfunctionaltheorywillbeoutlined.Recentprogresstoimprovetheefficiencyandspeedofthesecalculationsandtheirextensiontolargesystemswillbedescribed.

10

ContributedTalk

Moleculardynamicsstudyofself-assemblyofaqueoussolutionsofpoly[9,9-bis(4-sulfonylbutoxyphenylphenyl)fluorene-2,7-diyl-2,2’-bithiophene](PBS-PF2T)inthepresenceofpentaethyleneglycol

monododecylether(C12E5)

BeverlyStewart,HughDouglasBurrows

CentrodeQuímicadeCoimbra,ChemistryDepartment,UniversityofCoimbra,3004-535,Coimbra,PortugalE-mail:[email protected]

Thehighefficienciesobservedinphotosyntheticlightharvestingsystemsarearesultoftheir

elegantself-assembledstructures.Inordertomimicthesestructuresinsyntheticsystemsitisrequiredtobothcontrolandunderstandaggregation.Heretheuseofcomputationaltechniquesispresentedasamethodbywhichtoobservethebehaviourofasmallfluoreneconjugatedpolymerstructure[1].InterestliesprimarilyinthestudyofanionicPBS-PF2T[2]anditsobservedaggregationbehaviouraswellasthesignificanceofsurfactantpresenceuponthisaggregation.DynamicsimulationshavethusfarindicatedthataggregationofPBS-PF2T,andrelatedconjugatedpolyelectrolytes,isinhibitedinthepresenceofnon-ionicoxyethylenebasedsurfactantsCmEn[3],bywayofseparatingthepolymersandencapsulatingtheminliquidcrystallinesurfactantphases.HeretheeffectsofpentaethyleneglycolmonododecyletherC12E5,isinvesitgatedasanaggregationinhibitor.

Figure1.PBS-PF2TencapsulatedbyC12E5.Theimportanceofvariousinter-andintra-molecularinteractions,aswellassolventtemperature,willbediscussedascontributingfactors intheproductionofwell-definedaggregatedstructures.Byusingacomputationalapproachitispossibletodevelopanunderstandingofhowspecificfactorsaffectboththestructures and properties of aggregated systems and attempt to produce specific self-assembled

11

ContributedTalk

structureswhichmayoptimise theefficiencyofenergyandelectron transferprocesses in syntheticarchitectureswhichmimicthenaturalphotosyntheticlightharvestingcomplex.[1]Burrows,H.D.Tapia,M.J.Fonseca,S.M.Pradhan,S. Scherf,U.Silva,C.L.Pais,A.C.C.Valente,A.J.M.Schillén.K.Alfredsson,V.Carnerup.M.Tomišič,M.andJamnik,A.Langmuir2006,25,5545-5556.[2]Knaapila,M.Fonseca,S.M.Stewart,B.Torkkeli,M.Perlich,J.Pradhan,S.Scherf,U.Castro,R.A.E.andBurrows,H.D.SoftMatter,2014,10,3103-3111.[3]Burrows,H.D.Fonseca,S.M.Silva,C.L.Pais,A.C.C.Tapia,M.J.Pradhan.S.andScherf,U.Phys.Chem.Chem.Phys,2008,10,4420-4428.

12

ContributedTalk

Correlationconsistentbasissetsforthegroup1atomsK–Fr

J.GrantHill

DepartmentofChemistry,UniversityofSheffield,BrookHill,SheffieldS37HF,UKE-mail:[email protected]

Thecorrelationconsistentfamilyofbasissetsseealotofuseinhigh-accuracyabinitioquantum

chemistry [1,2],partlydue to their regularenergetic convergencecharacteristics leading toefficientcompletebasissetlimitextrapolationtechniques.Developmentsinultracold(<1mK)chemistrymeansaccuratecalculationsonmoleculescontainingheavyalkalimetals,suchasRbCs[3]areofinteresttoboththeoreticalandexperimentalgroupsworkinginthisarea,yetthereisalimitedchoiceofbasissetsforsuchmolecules.Withthismotivation,thedesignofcorrelationconsistentbasissetsforthegroup1atomsK–Frwillbepresented.Basissetstobeusedinconjunctionwithsmall-corepseudopotentialsoftheStuttgart-Masseyvariety[4],denotedcc-pVnZ-PP(n=D,T,Q,5),havebeenoptimisedalongwithall-electronDouglas-Krollsets,cc-pVnZ-DK(n=D–Q).Thesebasissetscanalsobeaugmentedwithdiffusefunctionsforthecalculationoflong-rangeinteractions,andwithadditionalfunctionsforthedescriptionofcore-valencecorrelation.ThevalidationoftheresultingbasissetsonthediatomicsM2,MHandMF(M=K,Rb,CsandFr),attheCCSD(T)leveloftheory,willalsobedescribed.Itisevidentthatcorrelationoftheoutercoreelectronsisvitalforcomputedspectroscopicconstantstoapproachexistingexperimentaldata.

[1]T.H.Dunning,Jr,J.Chem.Phys.,1989,90,1007-1023.[2]J.G.Hill,Int.J.QuantumChem.,2013,113,21-34.[3]P.K.Molony,P.D.Gregory,Z.Lietal.,Phys.Rev.Lett,2014,113,255301.[4]I.S.Lim,P.Schwerdtfeger,B.MetzandH.Stoll,J.Chem.Phys.,2005,122,104103.

13

ContributedTalk

RadicalSAMenzymes–Mechanism,dynamicsandradicalreactionprofiling

ChristofM.Jaegera,DamianoSpadoniaCharlesLaughtonbandAnnaK.Crofta

aDepartmentofChemicalandEnvironmentalEngineering,FacultyofEngineering,

UniversityofNottingham,UniversityPark,Nottingham,NG72RD,UKbFacultyofScience,UniversityofNottingham,UniversityPark,Nottingham,NG72RD,UK


Enzymes capable of controlling radicals present and wide range of radical-dependentmechanisms,with potential for applications inmedicinal and synthetic chemistry. The radical SAMenzymefamilyusesS-adenosylmethionine(SAM)asco-substrateorcofactortogenerateradicalsdirectlywithintheprotein.Whileageneralframeworkforthisinitialcatalyticmechanismhasbeenestablishedoverthepastyears,[1]muchlessisknownaboutthesubsequentchemicalrearrangementsinmostcases.Understandingofthesemechanismscanbeenhancedthroughtheuseofcomputationalapproaches.BesidesdetailedfullQM/MMmethods,combinedmoleculardynamicsand‘snapshot’(e.g.electronicstructure)methodscangivehighlybeneficiousinsightscomplementingoneanother.WepresentrecentresultsillustratinghowsuchcomputationalapproachescanbeusedtoshedlightontheradicalcontrolmechanismsutilisedinradicalSAMenzymes,particularlywithaviewtounderstandinghowtheseenzymesmightbothfacilitatedesiredconversionsandpreventunwantedsidereactions.Wealsofocusontheproblemthattheneedofthisdeeperunderstandingisalsothebottleneckforamore rapid access to rational enzyme design.Wewill show how radical reaction profiling throughcalculatingradicalstabilisationenergies(RSEs)[2]offersanattractivepossibilitytoassesschangesoftheoverall thermodynamicsof radical rearrangements as central steps in radical SAMenzymecatalysisthrough theexampleof the recently structurally resolvedbacterial7-carboxy-7-deazaguanine (CDG)synthase(QueE).[3]Acombinationofmoleculardynamics(MD)simulationsandquantummechanical(QM)calculationshasprovidednewinsightsintothemechanismofhowtheQueEenzymecontrolsitsradicalrearrangement,whichinvolvesaveryinterestingring-contractionstepandadditionalmetalcationbindingthatinfluencesthecatalysis.[4][1]J.B.Broderick,etal.,Chem.Rev.,2014,114,4229.[2]J.HioeandH.Zipse,.FaradayDisc.,2010.145,301.[3]D.P.Dowling,etal.,Nat.Chem.Biol.,2014,10,106[4]R.M.McCartyandV.Bandarian,Bioorg.Chem.,201243,15.

14

ContributedTalk

Oscillatingchargemigrationbetweenglycinelonepairssilencedbynucleardelocalisation:CASSCFEhrenfestdynamicsstudy

IakovPolyak,AndrewJenkins,MorganeVacher,MichaelJ.BearparkandMichaelA.

Robb

FacultyofNaturalSciences,DepartmentofChemistry,ImperialCollegeLondon,SouthKensingtonCampus,London,SW72AZ,UK


Recent advances in attosecond spectroscopy enabled a deeper insight into the electrondynamics following ionisation of molecules. Accordingly, theoretical studies in this field becomeincreasinglyimportant.Oneofthetime-dependentmethodsofchoiceisEhrenfestdynamics,andinourgroupwedevelopedasecond-orderEhrenfestdynamics,usingcompleteactivespaceself-consistentfield(CASSCF)toobtainaccuratetime-dependentelectronicwavefunctionsandcorrespondingenergieson-the-fly [1], which has been successfully used to study electron dynamics both at frozenmoleculargeometriesandcoupledtothedynamicsofnuclei.Animportantissuetoinvestigateisdecoherenceofelectrondensityoscillationsupon ionisation–ability topredictdecoherence isvital fordesigninganexperiment.Previouslywehaveshownthatchargeonglycinelonepairscoherentlyoscillateswithoutsignificantinteractionwithnuclearmotion[2].Inthecurrentworkourstudyrevealsfastdecoherenceofchargemigrationinglycinethathappensifappropriatesamplingoftheinitialnuclearwavepacketistakenintoaccount.Weinvestigatetheeffectofthechosenactivespaceonthefinalresultsaswellastrytogetinsightintothewaytheinitialwavepacketshouldbeconstructedtoprovideanaccuratedescriptionofelectrondynamics.

[1]M.Vacher,D.Mendive-Tapia,M.J.BearparkandM.A.Robb,Theor.Chem.Acc.,2014,133,1505.[2]M.Vacher,M.J.BearparkandM.A.Robb,J.Chem.Phys.,2014,140,201102.

15

ContributedTalk

UranylU-Oylstretchingvibrationsasaquantitativemeasureofequatorialbondcovalency:aquantumchemicalinvestigation

PoppyDiPietro1,AndyKerridge2

1DepartmentofChemistry,UniversityCollegeLondon,20GordonStreet,London,WC1H0AJ,UK

2DepartmentofChemistry,LancasterUniversity,Lancaster,LA14YB,UKe-mail:[email protected]

Theconceptofcovalencycanbeinterpretedinmanyways,anddifferentinterpretationsmay

leadtocontradictoryconclusions.Theoreticalapproachestounderstandingcovalentcontributionstobondingtypicallyemployeitheri)orbital-basedorii)density-basedanalysismethods1-2.Thecomplicatedelectron structure of actinide complexes, present due to the combined effects of relativity, strongelectron correlation andweak interactions with ligand fields can render orbital-based approachesambiguousbutthisinitselfisn’tjustificationforthevalidityofdensitybasedapproaches.

Hereweconsiderarangeofmodeluranylcomplexesanddemonstratethatcomplementarydescriptionsof covalent contributions to bonding derived from density based analyses are commensuratewithvariation in binding energies3. Furthermore, we demonstrate strong correlations between thesemeasuresandcalculatedU-Oylvibrationalfrequencies indicatingthat, inthesesystemsat least,suchvibrationscanbeconsideredaquantitativemeasureofequatorialbondcovalency.

Figure1.Densitydifferenceplotsandanalysisofthereduceddensitygradientof[UO2(NC)5]3-

[1]A.Kerridge,DaltonTrans.,2013,42,16428[2]A.Kerridge,RSCAdv.,2014,4,12078[3]P.DiPietroandA.Kerridge,Inorg.Chem.,2016,55,573

16

TCGGraduateStudentMeeting

TCGGraduateStudentMeetingExplicitlycorrelatedtreatmentoftransitionmetalcontainingsystems:Anongoingeffort……….17StellaKritikou(UniversityofSheffield)Quantumdynamicswithadaptivebasissetsandshort-timetrajectories……….18MaximilianA.C.Saller(UniversityofWarwick)PropertiesofBimetallicAuAgNanoparticlesforH2Production……….19AnnaGould(UniversityCollegeLondon)Capturingstaticcorrelationeffectswithoutusingmulti-referencemethods……….21JoshuaBlack(CardiffUniversity)Latticevibrationsinmolecularcrystals:polymorphismandphasetransitions……….22JonasNyman(UniversityofSouthampton)SinglebaseflippingmechanismsandkineticsinaDNAduplex:anenergylandscapeperspective……….23DebayanChakraborty(UniversityofCambridge)Applyingdirectquantumdynamicstophoto-excitedprocesses:Protontransferandchargemigration……….24ErynSpinlove(UniversityofBirmingham)Aninvestigationintocompetitionbetweenhalogenbondingandhydrogenbondinginmicrosolvated1-methyl-5-halouracil……….25SimonW.L.Hogan(UniversityofStAndrews)

17


Explicitlycorrelatedtreatmentoftransitionmetalcontainingsystems:Anongoingeffort

StellaKritikouandJ.GrantHill

DepartmentofChemistry,UniversityofSheffield,BrookHill,SheffieldS37HF,UK


Theexplicitlycorrelated(F12)abinitiomethodssignificantlyreducethebasissetdemandsofhigh-accuracy quantum chemistry, enabling meaningful coupled cluster and multi-referenceconfigurationinteractioncalculationstobecarriedoutonamuchwiderrangeofsystems.Advancesinbasis setsdesigned specifically foruse inF12calculationshavepushed thiseven further. ThereareexamplesintheliteratureofF12methodsnowbeingusedtoinvestigatetransitionmetalcomplexes,whichhastypicallybeenthereserveofdensityfunctionaltheory.Theaccuracyofexplicitlycorrelatedcoupledclustermethodsfor3dtransitionmeta-containingmoleculeswillbedemonstratedthroughanalysisofgeometriesandatomisationenergiesofarecentlyproposedtest set [1]. Comparison with experimental and composite thermochemistry derived data revealsacceleratedconvergencethatwilltranslatetosignificantcomputationalsavings.Nonetheless,explicitlycorrelatedcalculationsusingexistingbasissetsdonotalwaysconvergesmoothly,removingsomeoftheattractionofusingwavefunction-basedmethods.Inordertotacklethisproblem,correlationconsistentbasissetsforthe4dtransitionmetalelementsY-PdhavebeendevelopedandoptimisedspecificallyforusewithF12methods.Thesesetsaredesignedwithefficiencyandsmoothconvergenceinmind,andtheyholdthepromiseofaccuratecalculationsontransitionmetal-containingcomplexesofachemicallyrelevantsize.[1]X.Xu,W.Zhang,M.TangandD.G.Truhlar,J.Chem.TheoryComput.,2012,11,2036-2052.

18


Quantumdynamicswithadaptivebasissetsandshort-timetrajectories

MaximilianA.C.SallerandScottHabershon

DepartmentofChemistry,WarwickUniversity,Coventry,CV47AL

CentreforScientificComputing,WarwickUniversity,Coventry,CV47ALE-mail:[email protected]

The computational study of the quantum dynamics of non-trivial systems heavily relies on

efficientexpansionoftheinherentlycomplex,multidimensionalwavefunctiontofacilitatepropagationintime.Atpresent,basissetsemployedinquantumdynamicssimulationsgenerallyfallintooneoftwoclasses.Basissetswhich,afterhavinginitiallybeendistributedinphasespace,remainconstantthereafter,withtimepropagationbeingsolelyexpressedthroughvariationofasetofexpansioncoefficients,arecommonly referred to as being “time-independent”. Conversely, if basis functions are propagatedthroughphasespacealongsidetheircoefficients,theresultingbasissetistermed“time-dependent”.

Whiletheaforementionedstrategieshavebeenemployedinnumerous,successfulquantumdynamicssimulations,theybothcarrywiththemaninherentsetofdrawbacks[1].Duetotheirstaticnature,time-independentbasissetsmuststrivetodescribethewavefunctionacrossallofphasespaceatalltimes,basedonlyontheinformationavailableduringtheirinitialsampling.Inpractice,thisresultsinverylargebasissets,spanningallofrelevantphasespaceinagrid-likemanner,leadingtounfortunateexponentialscaling.Time-dependentbasissets,whileenabledbytheirdynamiccharactertoremainsmallerinsize,can violate energy conservation laws unless propagated using variational equations of motion.Furthermore,basisfunctionpropagationcansuffergreatlyfromnumericalill-conditioning.

Inarecentpublication[2],weintroducedanovelapproachtobasissetsamplingcapitalisingontheadvantagesofbothaforementionedstrategies,whileavoidingtheirdrawbacks.Wesamplephasespaceusing a set of trajectories to selectively place basis functions in regions relevant to wavefunctionpropagation.Treatingtheresultingbasissettime-independentlyyieldedveryencouragingresultsfortwochallengingbenchmarkproblems,namelytherelaxationdynamicsofphoto-excitedpyrazineandtheSpin-BosonHamiltonian.

Wearecurrentlyaimingtoaddressthekeyassumptionofthistechnique,namely,thevalidityofclassicaltrajectoriesasanapproximationtoquantumdynamics,whichisknowntoonlybesoundintheshorttimelimit.Wesubmitthatshortburstsoftrajectorysamplingwillresultinasmall,highlyaccurateadaptivebasisset,resampledandoptimizedviathematchingpursuitalgorithm.[1]S.Habershon,J.Chem.Phys.,136014109(2012)[2]M.A.C.Saller,S.Habershon,J.Chem.Theo.Comput.,118(2015)

19


PropertiesofbimetallicAuAgnanoparticlesforH2production

AnnaGouldab,AndrewJ.LogsdailbandC.RichardA.Catlowb

aUKCatalysisHub,ResearchComplexatHarwell,Oxon,Didcot,OX110FA,UKbKathleenLonsdaleMaterialsChemistry,DepartmentofChemistry,UniversityCollegeLondon,20GordonStreet,

London,WC1H0AJ,UKE-mail:[email protected]

Bimetallicnanoclusters(“nanoalloys”)arenanometre-sizedaggregatesthatexhibitdistinctive

properties from those associatedwith single atomsorbulkmatter.A varietyof sizes and chemicalarrangements are possible for nanoalloys, making them suitable for widespread application inengineering,magnetism,andcatalysis;Au−Agnanoalloyshavebeenshowntoimprovereactionturnover,incomparisontomonometallicalternatives,whenusedasco-catalystsforphotocatalyticH2production.Inthepresentedwork,wehaveinvestigatedthethermodynamicandkineticstabilityof147-atomAu-Agnanoalloys,asafunctionoftheirchemicalorderingandcomposition,usingdensityfunctionaltheory(DFT)and interatomic potentials (IPs). We determined the most thermodynamically stable chemicalarrangementsfordifferingAu:Agratios,andtheirelectronicpropertieswereevaluatedwithrespecttothephotocatalyticH2evolutionreaction[1].Wehavealsoexaminedtheinfluenceofheatingprocessesonthenanoclusters,ascalcinationproceduresareoftenrequired inexperimenttoremovecappingagentssuchaspolyvinylpyrrolidone(PVP).Thenanoclusterswereheatedfrom0–900K(NVT)usingIPmoleculardynamicsandweobservedlowtemperaturediffusionofAgcoreatomstothesurfaceforAg@Au (core@shell) nanoparticles, resulting in a pseudo-spherical geometry and altered chemicalproperties(Fig.1).ThislowtemperaturediffusionmayexplainwhytherearefewsuccessfulexperimentalreportsofAg@Ausynthesis,incomparisontoAu@Ag,asweillustratethatthestabilityofthischemicalarrangementsishighlydependentonshellthickness[2].Finally,wealsostudytheadsorptionofmolecularintermediariesonthenanoparticles,determiningtheirbindingstrengthandpossiblereactivity.TheCOmoleculeisofparticularinterest,asthiscanbeusedasaprobemoleculeexperimentally;IRstretchingfrequencyshiftsoftenreflectchangesinthenanoparticlemorphology or chemical arrangements. The calculated CO frequencies are compared with in situexperimental data, obtained from combined extended X-ray absorption fine structure and diffusereflectanceinfraredspectroscopy(EXAFS/DRIFTS).

20


[1]A.L.Gould,C.J.Heard,A.J.Logsdail,C.R.A.Catlow,Phys.Chem.Chem.Phys.2014,16,21049-21061.[2]A.L.Gould,A.J.Logsdail,C.R.A.Catlow,J.Phys.Chem.C.2015,119,23685-23697.

21


Capturingstaticcorrelationeffectswithoutusingmulti-referencemethods

JoshuaBlack

SchoolofChemistry,CardiffUniversity,MainBuilding,

ParkPlace,Cardiff,CF103AT,UKE-mail:[email protected]

Coupledclustertheoryisnowwidelyusedincomputationalchemistry,withCCSD(T)oftenbeingthedefactostandardforthecalculationofvariousmolecularproperties.Thisisduetoitssuccessincapturingthedynamicelectroncorrelationeffects.However,whenstaticcorrelationstartstobecomeimportantwithinasystem,suchasintransitionstatesandradicalmolecules,traditionalcoupledclustertheorycanproduceerroneousandunreliable results.Weproposeamethod,Quasi-Variational coupled clustertheory,whichisabletocapturebothdynamicandstaticeffects.Withour'blackbox'method,wecantheninvestigatethesechallengingchemicalsystemswithouttheneedtousetheexpensiveanddifficultmulti-referencemethods

22


Latticevibrationsinmolecularcrystals:Polymorphismandphasetransitions

JonasNymanandGraemeM.Day

SchoolofChemistry,UniversityofSouthampton,UniversityRoad,Southampton,SO171BJ,UK


Itispossibletopredicthowmoleculeswillcrystallisebyperforminganexhaustivesearchofallpossiblemolecularpackingalternativesandidentifyingthemostenergeticallyfavourablepackings.Thedevelopment of methods for Crystal Structure Prediction (CSP) is a rapidly growing field withincomputationalchemistry.Themostcommonmethodsrelyoncomputingthecohesiveenergybetweenthemolecules,whileignoringeffectsduetotemperatureandpressure.Latticevibrationalcalculationscanbeusedtoaccountforthermalcontributionsandhencehavethepotentialofimprovingtheoutcomeof crystal structure predictions and may reveal the temperature-dependence of the stabilities ofalternativecrystalforms,seeFig.1.

Figure1.Calculatedquasi-harmoniclatticefreeenergyofthreepolymorphsof2,2’-dipyridylamine(CSDref.DPYRAM).Wehaveimplementedcomputationallyveryefficientmethodsthatfacilitatelargescaleapplicationofharmonicandquasi-harmoniclatticedynamicstohundredsofpolymorphpairsortoentirelandscapesofpredictedcrystalstructures[1,2].Abenchmarkedandhighlyaccurateanisotropicforcefieldisusedtoperformrigid-moleculevibrationalcalculationstoobtainGibbsfreeenergiesofmolecularcrystals[3].Specialcareistakenindealingwithphonondispersioninawayrarelyaffordablewithelectronicstructuremethods.Ipresentresultsdemonstratingthatpolymorphsoforganicmolecularcrystalshaveverysmallenergy-andentropydifferences,whichhasimportantconsequencesforthepredictionanddevelopmentofmolecularmaterials.Inaddition,Idiscusstheimportanceofaccountingforthermalexpansionandtheprospectsofpredictingphasetransitions.

[1]J.Nyman,G.M.Day,CrystEngComm,2015,17,5154-5165[2]J.Nyman,G.M.Day,(inpreparation)[3]J.Nyman,O.SheehanPundyke,G.M.Day,(submitted)

23


SinglebaseflippingmechanismsandkineticsinaDNAduplex:anenergylandscapeperspective

DebayanChakraborty,KaushikSenandDavidJ.Wales

DepartmentofChemistry,UniversityofCambridge,LensfieldRoad,CB21EW,UnitedKingdom

Email:[email protected]

BaseflippingisanelementaryandlocalizeddeformationofaDNAfragment,initiatedbytheruptureofWatson-Crickinteractionsatatargetbase-pair,followedbyextrusionofoneofthebasestoanextrahelicalposition.Onextrusion,thegeneticinformationotherwiseencoded,becomesaccessibletoenzymes.InmanyimportantcellularprocessessuchasDNAtranscriptionandreplication,baseflippingconstitutesakeystep.Inaddition,thereisgrowingevidencetosuggesttheimportanceofbaseflippinginDNAdamagerecognitionbyrepairenzymes.Despiteawealthofexperimentalandtheoreticalstudies,themicroscopicdetailsofbaseflippingmechanismsandkineticsarenotclearlyunderstood.Inthiswork,weemploytheDiscretePathSamplingmethodinconjunctionwithanall-atompotentialandanimplicitsolventmodeltoinvestigatetheflippingmechanismsandkinetics inaB-DNAduplex, intermsof itsunderlyingenergylandscape.Wefindthatbaseflippingcanoccureitherviathemajororminorgrooves,inagreementwithprevioussimulations.Furthermore,theflippingtimescalesareestimatedtobeinthemillisecondregime,consistentwithimino-protonexchangeexperiments.Ourresultsalsodemonstratethatevenforlocaldeformationssuchasbase-flipping,aperfectstructuralorderparametermaynotexist,andthereforehighlightthepitfallsofusinglow-dimensionalprojectionsoftheenergylandscape.

24


Applyingdirectquantumdynamicstophoto-excitedprocesses:Protontransferandchargemigration

KaiteErynSpinloveandGrahamWorth

SchoolofChemistry,CollegeofEngineeringandPhysicalSciences,UniversityofBirmingham,Edgbaston,Birmingham,B152TT,UK


Inordertounderstandphoto-excitedprocessesithasbeenproventobeimportanttodescribesignificantquantumeffectssuchastunnellingandconicalintersections.Amethodofdirectquantumdynamicsforthestudyofsuchphoto-excitedprocesseshasrecentlybeenimplementedintheQuanticssoftwarepackage.TheDD-vMCG (directdynamicsby thevariationalmulti-configurationalGaussian)methodpromisestobefast,efficient,andwithbetterconvergencepropertiesthanpreviousmethodsbasedonclassicaltrajectories[1].Asitisinthedevelopmentphase,testingisrequired.TheunderlyingphysicalprocessesbywhichmutagenesisoccursinDNA/RNA,whetherbyUVradiationorspontaneous occurrence, has been the subject of extensive chemical and biological research.Prototypically the inter- and intra-molecular proton-transfers in excited states of 2-pyridone/2-hydroxypyridineandFormamide/Formamidicacidhavebeenusedasanaloguestothedescriptionofmutagenesis.Theypresentan interesting systemto studywith theDD-vMCGmethodas theymaydemonstratecompetitionbetweenproton-transferandnon-adiabaticcurvecrossing[2,3].Another photo-excited process of interest is the competition between charge-transfer and charge-migration.Anewdirectdynamicsmethod,basedontheEhrenfestapproach,hasbeenusedpreviouslytostudycharge-migrationintheToluenecation[4].AmodelHamiltonianfortheAllene(C3H4)radicalcationhasbeenusedasatestinpreviousQuanticsstudiesoncharge-transfer[5],andpresentsanidealsystemtotesttheEhrenfestapproach.[1]G.Richings,etal.,Int.Rev.Phys.Chem,.2015,34,269.[2]Q-S.Li,etal.,J.Phys.Chem.A,2005,109,3983.[3]L.Poisson,etal.,PCCP,2014,16,581[4]M.Vacher,elal.,J.Phys.Chem.A,2014,119,5165.[5]G.WorthandL.Cederbaum,Chem.Phys.Lett.,2001,348,477

25


Aninvestigationintocompetitionbetweenhalogenbondingandhydrogenbondinginmicrosolvated1-methyl-5-halouracil

SimonW.L.HoganandTanjavanMourik

EaStCHEMSchoolofChemistry,UniversityofStAndrews,StAndrews,KY169ST,UK


Aninvestigationintohalogenbondingandhydrogenbondinginteractionsbetweenamoleculeof1-methyl-5-halouracil(XU)(X=F,Cl,Br,I,orAt)andawatermolecule(XU-w)ortwowatermolecules(XU-2w),primarilyintheregionbetweentheC5-X5bondandtheC4=O4bondwasperformed[1].ForallcalculationstheM06-2Xfunctionalwasusedinconjunctionwitheitherthe6-31+G*basisset(forallelementslighterthaniodine)oraug-cc-pVDZ-PP(foriodineandastatine).ForXU-whalogenbondswerefoundtoformbetweenX5andthewateroxygenatom(Ow)whereXisBr,IorAt;whilethatinteractionwasfoundforX=Cl,Br,IorAtinthecaseofXU-2w.InthecaseofXU-2wthestructurewithahalogenbondalsoincludedwater-waterandwater-O4hydrogenbonds.ForXU-wallofthehalogenbondedminimawerefoundtobeconnectedtoahydrogenbondedminimumviaatransitionstate,andthegeometryandbarrierheightofeachtransitionstatewascomputed.Allminimaandtransitionstateswereconfirmedbyharmonicvibrationalfrequencyanalysis.Inallcasesthestrengthofthehalogenbond,thebarrierheightandlinearityoftheC5-X5-Owangleincreasesasthehalogengroupisdescended.Alloftheseobservationsareattributedtothegreaterpolarisability(andhencestrongersigmaholeeffect)asthehalogenbecomesheavier.ThelackofahalogenbondedClU-wdespiteitspresenceinthecaseofClU-2wisascribedtothestrongercompetingwater–O4hydrogenbond.ThepresenceofhalogenbondswithaC5-X5-Owangleintherange150°-160°degreesdemonstratestheflexibilityofthehalogenbondindepartingfromitsidealangle(linear)whentherearesecondaryfactorsbearingonthegeometryascanbefoundintherelativelycomplexchemicalenvironmentoftheXU-2wsystems.

Figure1:The1-methyl-5-halouracilpluswatersystem.X=F,Cl,Br,IorAt[1]S.W.L.HoganandT.vanMourik,J.Comput.Chem.,2016,37,763-770.

Xbondexample(AtXbond)

N3

C2

N1C6

C5

C4

X5

O4

Ow

Hw1

Hw2

26

Poster

PostersModellingtryptophantohemeelectrontransferandexcitationenergytransferinmyoglobin……….28ChristianSuess(UniversityofNottingham)TunnelingdynamicsofHF-H2Oonanaccurateanalyticpotential……….29ChuhuiXiao(UniversityofBristol)Anomalouspropertiesinnetworkmaterials……….30DomagojFijan(UniversityofOxford)AcomputationalstudyofGe5O(PO4)6……….31GregorMcInnes(UniversityofSt.Andrews)Gas-phaseandMgO(100)-supportedAu,Pd,andAuPdsub-nanometreclusters:Structuresandenergeticanalysis……….33HeiderA.Hussein(UniversityofBirmingham)Currentdensity-functionaltheoryusingmeta-generalizedgradientexchange-correlationfunctionals……….34JamesW.Furness(UniversityofNottingham)Structuresandenergylandscapesofmicro-hydratedClO3

-andClO4-

clusters……….35JohnC.Hey(UniversityofBirmingham)Cyclicbreakdownofringcurrentsusinggraphtheoreticalmethods……….36JosephClarke(UniversityofSheffield)Network-basedanalysisofmodelphotosyntheticsystems……….37LewisA.Baker(UniversityofWarwick)EffectofgraphenesupportonlargePtnanoparticles……….38LucasG.Verga(UniversityofSouthampton)Photo-excitedmoleculardynamicsofmoleculesassociatedwiththegreenfluorescentprotein……….39MarcusP.Taylor(UniversityofBirmingham)

27

Poster

Isotopeeffectcalculationsinthesupramolecularage……….40PhilippeB.Wilson(UniversityofBath)Aforcefieldfortheaccuratecalculationofthestructureandvibrationalspectroscopyofcarbonmaterials……….41PriteshTailor(UniversityofNottingham)AnewhybridfunctionalforDensityFunctionalTheoryinspiredbytheUnsoldapproximation……….42TimWiles(BristolUniversity)Vibrationalstructuresinthenear-UVelectroniccirculardichroismspectraofproteins……….43ZhuoLi(UniversityofNottingham)

28

Poster

Modellingtryptophantohemeelectrontransferandexcitationenergytransferinmyoglobin

ChristianSuess,NicholasA.BesleyandJonathanD.Hirst

SchoolofChemistry–UniversityofNottingham,UniversityPark,Nottingham,NG72RD,UK


Electrontransfer(ET)isamongstthemostimportantchemicalprocesses,andareubiquitousthroughout nature. This has motivated the development of experimental techniques in order tocharacterisepathwaysof electron transfer andenergy transfer inproteins inmoredetail. Recently,Cherguiandco-workersusedtwo-dimensionalultraviolet(2D-UV)spectroscopytostudytheultrafastelectrontransferinmyoglobin[1].Myoglobinactsasanoxygencarrierinmuscletissueandcomprisesasinglepolypeptidechainof153aminoacidswithanironporphyrinactivesite.The2D-UVstudyfocusedontheETandexcitationenergytransfer(EET)betweenthetwotryptophanresidues(7Trpand14Trp)andtheheme.AshemeproteinsdonotfluoresceitisdifficulttodistinguishbetweenETorEEThencehowelectronsdecayremainsambiguous.Inthisposterwedescribethemodellingoftheseprocessesbaseduponquantumchemicalcalculations.Singleexcitationconfigurationinteraction(CIS)andtime-dependent density functional theory (TDDFT) are usedwithin the framework ofMarcus theory toestimatetheratesoftryptophantohemeETandEET.Keyintermediateresiduesbetweenthedonorandacceptorareidentifiedusingthepathwaystunnellingmodel,andtheinclusionoftheseresiduesiscriticalinTDDFTcalculationsoftheelectroncouplingmatrixelements.Strategiestoreducethecostofthecalculationssuchasusingarestrictedexcitationsubspacemethod[2]areexplored.Itisshownthat14Trpexcitationdecaysbyelectrontransfertothehemeonamuchfastertimescalethantheexcitationenergytransferprocesswhilst7Trprelaxesbyexcitationenergytransfertothehemefasterthantheelectrontransfer.

[1]C.Consani,G.Auböck,F.vanMourik,M.Chergui.Science,2016,339,1586-9.[2]Besley,N.A.ChemicalPhysicsLetters390,124-129.(2004)

29

Poster

TunnelingdynamicsofHF-H2Oonanaccurateanalyticpotential

ChuhuiXiaoandDavidP.Tew

SchoolofChemistry,UniversityofBristol,Bristol,BS81TH,UKE-mail:[email protected]

Thehydrogenbondis importantduetoitsdominantroleinnaturalscience.TheHF-H2O

complex, the simplest hydrogen halide-water complex, has received attention from bothexperimentalistsandtheoreticians[1].Experimentalspectra,however,arehardtoobtainbecauseofthelowvolatilityofwaterandhydrogenfluoridemixture[2]andhardtoassignduetothetunnelingdynamics[3].Abinitiocalculationofro-vibrationalenergylevelsonanaccurateelectronicpotentialcanprovide much needed insight.We built a potential energy surface (PES) by the least absoluteshrinkageandselectionoperator(LASSO)regressionandfitto10000CCSD(T)-(F12*)energiesatrandomgeometries [4]. LASSO regression is the state-of-the-art linear regression that canminimizeoverfittingbyconstrainedconditionswhenaddingamassivelyamountoffunctions.Thegeometriesand frequencies both attheequilibriumandtransitionstateobtained fromPESagreecloselywiththeabinitioresults.Additionally,thebarriertoinversionis126.55cm-1 forabinitiocalculationand132.39cm-1forPES,bothofwhichareclosetotheexperimentaldata,126cm-

1[5].Theconvergedtunnelingenergylevelsarealsoobtainedusingfull-dimensionalvibrationalapproach–VSCFandVCI,usingtheReactionPathHamiltonian[6].

Figure1.StructuresofHF-H2Ocomplex.(1)FH-OH2withCssymmetry, (2)FH-OH2withC2vsymmetry[1]V.P.Bulychev,E.I.Gromova,andK.G.Tokhadze,Opt.Spectrosc+.,2004,96,774-788.[2]R.K.Thomas,Proc.R.Soc.A.,1975,344,579-592.[3]S.P.Belov,V.M.Demkin,N.F.Zobov,E.N.Karyakin,A.F.Krupnov,andI.N.Kozin,J.Mol.Spectrosc.,2007,241,124-135.[4]WataruMizukami,ScottHabershon,andDavidP.Tew,J.ChemPhys.,2014,141,144310-144319.[5]A.C.LegonandD.J.Millen,FaradayDiscussChem.Soc.,1982,73,71-87.[6]W.H.Miller,N.C.Handy,andJ.E.Adams,J.Chem.Phys.,1980,72,99-112.

30

Poster

Anomalouspropertiesinnetworkmaterials

DomagojFijanandMarkWilson

DepartmentofChemistry,PhysicalandTheoreticalChemistryLaboratory,UniversityofOxford,SouthParksRoad,OxfordOX13QZ,UnitedKingdom

E-mail:[email protected];[email protected]

Thermodynamic and kinetic anomalies are often encountered in tetrahedral liquids, mostfamously inwater(forexample,thedensityanomaly).Theoriginoftheanomalies isoftenlinkedtobehaviour of quantities associated to phase transition phenomena which occur in the metastablesupercooledregimethatislargelyinaccessiblebyconventionalexperiments.Asaresultsimulationsareoften used to explore this problem. Several theories and scenarios have been proposed that linkbehaviourofanomalouspropertiestotheexistenceofaliquid-liquidcriticalpoint[1][2][3].Stillinger-Weber(SW)potentialsareoftenemployedtomodeltetrahedralliquids.Thesepotentialsarecomposedofastandardpairwisetermwithexponentialdecayandatriplettermwhichpenalizesdeviationsfromidealtetrahedralangles[4].InrecentyearsthecriticalpointforSWsiliconhasbeenuncovered[5]andlociofanomalouspropertiescalculatedforconstantpressurefordifferentstrengthsoftripletterminSWpotential[6].However,nosystematicstudyoftheSWpotentialthatinvolvesthecalculationofcriticalpointsandspinodallinesandlinksthemtoanomalouspropertiesasafunctionofthestrengthoftriplettermhasyetbeenreported.InthisstudywetakeasystematicapproachtoexploretheparameterspaceofthetriplettermintheSWpotentialatvarioustemperatures,pressuresanddensities.Thisenablesustomorethoroughlyunderstandtheappearanceofthermodynamicandkineticanomaliesintetrahedralliquidsandtheirconnectiontotheunderlyingtetrahedralityofthesystem.

[1]R.J.Speedy,JournalofPhysicalChemistry,1982,86(6),982–991.[2]S.Sastry,P.G.Debenedetti,F.SciortinoandH.E.Stanley,Phys.Rev.E1996,53(6),6144–6154.[3]P.H.Poole,F.Sciortino,U.EssmannandH.E.Stanley,Nature,1992,360(6402),324–328.[4]F.H.StillingerandT.Weber,Phys.Rev.B,1985,31(8),5262–5271.[5]V.V.Vasisht,S.SawandS.Sastry,NaturePhysics,2011,7(7),549–553.[6]W.Hujo,B.S.Jabes,V.K.Rana,C.ChakravartyandV.Molinero,JournalofStatisticalPhysics,2011,145,293–312.

31

Poster

AcomputationalstudyofGe5O(PO4)6

GregorMcInnes,MarkTham,JohnIrvineandHerbertFrüchtl

Eastchem,SchoolofChemistry,UniversityofSt.Andrews,NorthHaugh,St.Andrews,KY169ST,UKE-mail:[email protected]

SolidOxideFuelCells(SOFCs)arebeinginvestigatedforuseaspossiblegreenenergystorage

devices.ThiscomputationalstudyisbasedonpracticalworkconductedonGe5O(PO4)6whichisbeingconsideredforuseasapossibleelectrolytematerialandattemptstofindthemigrationpathwaythoughthestructureusedbyoxygen.ThecrystalstructureofGe5O(PO4)6consistsofGeO6octahedraandGeO4tetrahedralinkedbyPO4groupsforminga3dimensionallattice.

Figure1.ProjectionofGe5O(PO4)6wherea)istheunitcellshowingtheatomscrystallograpicallydefinedasGe1 (purple), Ge2 (Green),Ge3 (light blue) and phosphorus (grey). b) shows the oxygen atomscrystallographicallydefinedasO1(red),O2(yellow),O3(black),O4(pink)andO5(purple)Practicalworkhasshownthatthismaterialhasaconductivityofof1.1x10-4Scm-1forbulkprocesses.Thiscorrespondstoanactivationenergyof0.35eVfortheoxygenmigrationprocess.Thisactivation

32

Poster

energyinconjunctionwithresultsappearingtoshowthatO1(showninfigure1)ismobile,hasresultedintheproposalthatoxygenmigrationoccursalongthec-axisofthelatticeinvolvingthemovementoftheO1oxygenalongthelatticeinaninterstitialcymechanism.Thiscomputationalstudylooksatpossiblepathwaysthroughthelatticeinanattempttofindoutiftheproposedpathwayiscorrect,andifnot,thenattempttofindapathwaywhichfitswiththeobservedexperimental results.Wehave so farusedNudgedElasticBand calculations to investigatedifferentvacancymechanisms throughthe lattice.The lowestenergypathwaywehave foundso farusingavacancyorinterstitialcymechanismoccursthroughthea/b-axisandwithanactivationbarrierof2eV,withmovementalongthec-axisshowingamuchhigherbarrier,sothatthelattercanberuledout.Theenergydifferencebetweenthelowestenergypathwayandtheexperimentalresultsleadsustoconcludethatyetanotherpathwaymustbepresent.Morepathwaysarenowbeinginvestigatedwithafocusonpathways involving an alternative lattice structure that has been shown to be present within theGe5O(PO4)6electrolyte(showninfigure2)

Figure2.ApossiblealternativelatticestructureforGe5O(PO4)6

33

Poster

Gas-phaseandMgO(100)-supportedAu,Pd,andAuPdsub-nanometreclusters:structuresandenergeticanalysis

HeiderA.Hussein,1,2RoyL.Johnston1

1SchoolofChemistry,UniversityofBirmingham,Birmingham,UnitedKingdom2DepartmentofChemistry,CollegeofScience,UniversityofKufa,Najaf,Iraq


Sub-nanometreclusterscanbedefinedasgroupsoraggregatesofafewtotensofmetalatomswhicharebelow1.0nminsize.Theseclustersmaycontainthesameatoms,givingpureclusters,ortwoormoredifferentatomspresentinghetero-clusters. Inthisproject,TheBirminghamParallelGeneticAlgorithm(BPGA)hasbeenadoptedfortheglobaloptimizationoffreeandMgO(100)-supportedPd,AuandAuPdnanoclusterstructures,overthesizerange4-10atoms.Structureswereevaluateddirectlyusingdensityfunctionaltheory,whichhasallowedtheidentificationofPd,AuandAuPdglobalminima.Theenergetics,structures,andtendencytowardssegregationhasbeenevaluatedusingdifferentstabilitycriteria suchasbindingenergy,excessenergies,andseconddifference inenergy.Theabilityof thesearchestofindtheputativeglobalminimumhasbeenassessedusingahomotopsearchmethod,whichshowsahighdegreeofsuccess.

34

Poster

Currentdensity-functionaltheoryusingmeta-generalizedgradientexchange-correlationfunctionals

JamesW.Furness1,JoachimVerbeke1,AndrewM.Teale1,ErikI.Tellgren2,Stella

Stopkowicz2,UlfEkström2andTrygveHelgaker2

1SchoolofChemistry,UniversityofNottingham,Nottingham,UK

2CentreforTheoreticalComputationalChemistry,UniversityofOslo,Oslo,NorwayE-mail:[email protected];[email protected]

Wepresenttheself-consistentimplementationofcurrent-dependent(hybrid)metageneralized

gradientapproximation(mGGA)densityfunctionalsusingLondonatomicorbitals.Apreviouslyproposedgeneralizedkineticenergydensity[1,2]arisingnaturallyfromconsiderationofthesphericallyaveragedexchangehole[3], is utilized to implementmGGAs in the frameworkof Kohn-Shamcurrentdensityfunctional theory (KS-CDFT). A unique feature of the non-perturbative implementation of thesefunctionalsistheabilitytoseamlesslyexploreawiderangeofmagneticfieldsupto1a.u.(~235000T)instrength.CDFTfunctionalsbasedontheTPSS[4]andB98[5]formsareinvestigatedandtheirperformanceisassessedbycomparisonwithaccurateCCSD(T)data[6].IntheweakfieldregimemagneticpropertiessuchasmagnetizabilitiesandNMRshieldingconstantsshowmodestbutsystematicimprovementsoverGGAfunctionals.However,instrongfieldregimethemGGAbasedformsleadtoasignificantlyimproveddescriptionoftherecentlyproposedperpendicularparamagneticbondingmechanism[7],comparingwellwithCCSD(T)data[8].Incontrasttofunctionalsbasedonthevorticity[9]theseformsarefoundtobenumericallystable[10]andtheiraccuracyathighfieldsuggeststheextensionofmGGAstoCDFTviathegeneralizedkineticenergydensityshouldprovideausefulstartingpointforfurtherdevelopmentofCDFTapproximations[11].[1]A.D.Becke,Can.J.Chem.74,995(1996)[2]J.Tao,Phys.Rev.B.71,205107,(2005)[3]J.F.Dobson,J.Chem.Phys.98,8870(1993)[4]J.Tao,J.Perdew,V.StaroverovandG.E.Scuseria,Phys.Rev.Lett.91,146401(2003)[5]A.D.Becke,J.Chem.Phys.109,2092(1998)[6]A.M.Teale,O.B.Lutn_s,T.Helgaker,D.J.Tozer,J.Gauss,J.Chem.Phys.138,024111(2013)[7]K.K.Lange,E.I.Tellgren,M.R.Ho_mann,T.Helgaker,Science337,327(2012).[8]S.Stopkowicz,K.K.Lange,E.I.TellgrenandT.Helgaker,arXiv:1505.08045v1,(2015)[9]G.VignaleandM.Rasolt,Phys.Rev.B.37,10685(1988)[10]E.Tellgren,A.M.Teale,J.W.Furness,K.K.Lange,U.Ekstr�omandT.Helgaker,J.Chem.Phys.140,034101(2014)[11]J.W.Furness,J.Verbeke,E.I.Tellgren,S.Stopkowicz,U.Ekstrm,T.Helgaker,A.M.Teale,arXiv:1505.07989,(2015)

35

Poster

Structuresandenergylandscapesofmicro-hydratedClO3-and

ClO4-clusters

JohnC.Hey,EmilyJ.DoyleandRoyL.Johnston

SchoolofChemistry,UniversityofBirmingham,Birmingham,B152TT,UK


Electrolyticsolutionsareextremelyimportantinbothbiologyandindustry,asthepropertiesofsolutionscanbedrasticallyalteredbythepresenceofsalts.1Saltshavelongbeenknowntoaffectthesolubilityandstabilityofproteinsinsolution,in1888,HofmeisterandLewithdevisedanorderingforseveralcommonions,rankingthemaccordingtothiseffect,thisorderingisknownastheHofmeisterseries.2–5Perchlorate(𝐶𝑙𝑂%&)andChlorate(𝐶𝑙𝑂%&)arebothhighlychaotropicHofmeisterions,inthattheypromotedisorderwithinthehydrogenbondingnetworkandreducethesolubilityofproteins.6,7Sulfate(𝑆𝑂%)&)ontheotherhandisakosmotropicHofmeisterion,whichincreasesproteinstabilityandpromotesorderwithinthehydrogenbondingframeworkofwater.8–11Inthisworkwefindlowenergyconformationsformicro-hydratedperchlorateandchlorateclusterswith𝑁+,- ≤ 12watersandpresentputativeglobalminima.Theselowenergyconformationswerefoundusingabasin-hoppingsearchwithempiricalpotentialsforthehalo-oxyanionandtheTIP4Ppotentialforwater,usingthepelesoftwarepackageontheBlueBEARHPCcluster.ThesestructureswerethenlocallyminimisedattheDFTlevelusingtheB3LYPexchange-correlationfunctionalandthe6-311++G**basisset.6,12–16 Theenergy landscapesof the chlorateandperchlorate clusters are thenexploredusingadoubly-nudgedelasticbandmethodandvisualisedasdisconnectivitytreesbeforebeingcomparedtooneanotherandtoSulfatetogiveacomparisonoftwodifferentchaotropeswithastronglykosmotropicion.17[1]A.P.dosSantosandY.Levin,FaradayDiscuss.,2013,160,75–87[2]W.J.XieandY.Q.Gao,J.Phys.Chem.Lett.,2013,4,4247–4252[3]M.T.Record,E.Guinn,L.PegramandM.Capp,FaradayDiscuss.,2013,160,9–44[4]M.G.Cacace,E.M.LandauandJ.J.Ramsden,Q.Rev.Biophys.,1997,30,241–277[5]W.Kunz,Curr.Opin.ColloidInterfaceSci.,2010,15,34–39[6]M.D.Baer,I.-F.W.Kuo,H.BluhmandS.Ghosal,J.Phys.Chem.B,2009,113,15843–15850[7]G.M.BrownandB.Gu,Thechemistryofperchlorateintheenvironment,Springer,2006[8]L.C.Smeeton,J.D.Farrell,M.T.Oakley,D.J.WalesandR.L.Johnston,J.Chem.TheoryComput.,2015,11,2377–2384[9]N.Mardirossian,D.S.Lambrecht,L.McCaslin,S.S.XantheasandM.Head-Gordon,J.Chem.TheoryComput.,2013,9,1368–1380[10]D.S.Lambrecht,G.N.I.Clark,T.Head-GordonandM.Head-Gordon,J.Phys.Chem.A,2011,115,11438–54[11]J.T.Obrien,J.S.Prell,M.F.BushandE.R.Williams,J.Am.Chem.Soc.,2010,132,8248–8249[12]Pythonenergylandscapeexplorer:http://pele-python.github.io/pele/Accessedon:03/12/2015.[13]D.J.WalesandJ.Doye,J.Phys.Chem.A,1997,93,5111–5116[14]D.J.WalesandH.A.Scheraga,Science(80-.).,1999,285,1368–1372[15]S.KazachenkoandA.J.Thakkar,Chem.Phys.Lett.,2009,476,120–124[16]D.J.WalesandM.P.Hodges,Chem.Phys.Lett.,1998,286,65–72[17]S.A.TrygubenkoandD.J.Wales,J.Chem.Phys.,2004,120,2082–2094

36

Poster

Cyclicbreakdownofringcurrentsusinggraphtheoreticalmethods

JosephClarkeandPatrickFowler

DepartmentofChemistry,UniversityofSheffield,SheffieldS37HF,UKE-mail:[email protected]

The graph theoretical model of conjugated-circuit methods1 gives a qualitatively correct

calculationoftheringcurrentsofbenzenoids.Themodelcanbeapproximatelycomparedwiththe‘goldstandard’ofHückel-London2andfullabinitiocalculations.3However,conjugated-circuitmodelshavefundamental flaws when applied to some simple systems, such as cyclopentadiene. Furthermore,conjugated-circuitmodelsgiveverysimpleinterpretationsforisland-likesystems,suchasperylene,butmaybetoosimpleforextensions.Wedescribeacycle-decompositionoftheHückelmethodthatgivesanalysisof cyclecontributions tocurrentandshouldallowcalibrationofnewconjugatedcircuit-likemodelsofringcurrentsthatapplymuchmorewidelythanthepresentKekuléan-onlymodels.[1](a)Randić,M.,Chem.Phys.Lett.,2010,500,123-127.(b)Mandado,M.,JournalofChemicalTheoryandComputation,2009,5,2694-2701andSupplementaryInformation.(c)Ciesielski,A.;Krygowski,T.M.;Cyranski,M.K.;Dobrowolski,M.A.;Aihara,J.-i.,PCCP,2009,11,11447-11455.(d)Fowler,P.W.;Myrvold,W.,TheJournalofPhysicalChemistryA,2011,115,13191-13200[2](a)London,F.,J.Phys.Radium,1937,8,397-409.(b)McWeeny,R.,Mol.Phys.,1958,1,311.(c)Pople,J.A.,Mol.Phys.,1958,1,175[3]Steiner,E.;Fowler,P.W.,J.Phys.Chem.A,2001,105,9553-9562

37

Poster

Network-basedanalysisofmodelphotosyntheticsystems

LewisA.BakerandScottHabershon

DepartmentofChemistryandCentreforScientificComputing,UniversityofWarwick,Coventry,UK.E-mail:[email protected]

Pigment-proteincomplexes(PPCs)playacentralrole infacilitatingexcitationenergytransfer

(EET) from light-harvesting antenna complexes to reaction centres in photosynthetic systems;understandingmolecularorganisationinthesebiologicalnetworksiskeytodevelopingbetterartificiallightharvestingsystems.Wecombinequantum-mechanicalsimulationsandanetwork-basedpictureoftransporttoinvestigatehowchromophoreorganisationandproteinenvironmentinPPCsimpactsonEETefficiencyandrobustness[1-3].FocusingontheFenna-Matthews-Olson(FMO)complexandthelightharvestingcomplex(LHCII),weconsidertheimpactonEETefficiencyofbothdisruptingthechromophorenetworkandchangingtheinfluenceof(localandglobal)environmentaldephasing.Surprisingly,wefinda large degree of resilience to changes in both chromophore network and protein environmentaldephasing,theextentofwhichisgreaterthanpreviouslyobserved;forexample,FMOandLHCIImaintainEETwhen50%oftheconstituentchromophoresareremoved.Overall,theserobustnessandefficiencycharacteristics areattributed to thehighly connectednatureof the chromophorenetworkand thepresenceofmultipleEETpathways,featureswhichmighteasilybebuilt intoartificialphotosyntheticsystems.

Figure1.Modelreductionoftheenergytransportpathwayingreensulphurbacterium.[1]A.EisfieldandJ.Briggs,Phys.Rev.E,2012,85,046118.[2]J.Moix,J.Wu,P.Huo,D.Coker,andJ.Cao,J.Phys.Chem.Lett.,2011,2,3045.[3]L.BakerandS.Habershon,J.Chem.Phys.,2015,143,105101.

38

Poster

EffectofgraphenesupportonlargePtnanoparticles

LucasG.Verga,AndreaRussell,Chris-KritonSkylaris

DepartmentofChemistry,UniversityofSouthampton,UniversityRoad,Southampton,SO171BJ,UKE-mail:[email protected]

Duringthelastdecades,theinterestinmorepowerfulandflexiblewaystogenerateenergy,such

asthefuelcelltechnology,isconstantlyincreasing.Fuelcellsarecapableofproducingelectricalenergywithhigherefficiencyandautonomyandmayhelptoreducethedependenceonfossilfuelsandlowertheemissionoftoxicproductsintotheatmosphere.Specifically,thedirectmethanolandethanolfuelcells,DMFCsandDEFCS,areemergingtechnologieswithseveralpossibleapplicationsduetotheeasinessofhandlingthesefuels,theirhighenergydensity,lowpollutantemission,andlowworkingtemperatures.OneofthemainchallengesonDEFCsisthesearchforefficientcatalystsfortheethanoloxidationreaction,EOR[1],andtheoxygenreductionreaction,ORR[1].Nowadays,state-of-the-artcatalystsarecreatedviadepositionofmonolayersornanoparticlesofthecatalyticmaterialoversupports,increasingtheactivesurfaceareaanddecreasingtheloadingofcatalyticmaterialand,consequently,theoverallcostoffuelcells[1]–[3].Therefore,theunderstandingabouttheinteractionbetweencatalystandsupportcanbeessentialtodesigningefficientDEFCscatalysts.Here,weemploylarge-scaleDFTsimulationsformetallicsystems[4]asimplementedintheONETEPlinear-scalingDFTprogram[5]tostudyplatinumclustersinteractingwithasinglelayergraphene.Wecomparethestabilityofplatinummonolayersandnanoparticlesinteractingwiththesupport,andanalyseitsoptimisedgeometriesandelectronicproperties.Ourresultsshowthatnanoparticlesaremorestablethanmonolayers, and that the difference between their stabilities increases with the system size.Moreover, our optimized platinum structures exhibit inter-atomic expansion in facets close to thegraphenesheet,andtheelectronicanalysisshowselectrontransferfromtheplatinumclusterstothesupport.BotheffectscanchangethecatalyticbehaviourofthePtnanoparticles,showingtheimportanceofdeeperunderstandingofthesupporteffects.[1]J.FriedlandU.Stimming,ElectrochimicaActa.,2013,101,41.[2]M.Shao,Q.Chang,J.-P.Dodelet,andR.Chenitz,Chem.Rev.,2016,116,3594.[3]S.Navalon,A.Dhakshinamoorthy,M.Alvaro,andH.Garcia,Coord.Chem.Rev.,2016,312,99.[4]Á.Ruiz-SerranoandC.-K.Skylaris,J.Chem.Phys.,2013,139,054107.[5]C.-K.Skylaris,P.D.Haynes,A.A.Mostofi,andM.C.Payne,J.Chem.Phys.,2005,122,084119.

39

Poster

Photo-excitedmoleculardynamicsofmoleculesassociatedwiththegreenfluorescentprotein

MarcusP.TaylorandGrahamA.Worth

SchoolofChemistry,UniversityofBirmingham,Edgbaston,Birmingham,B152TT


Therehasbeenimmenseinterestinthegreenfluorescentprotein(GFP)duetoit'splethoraofpotentialapplicationsand,asyet,lackoffulldetailsurroundingitsphotophysics.[1,2]Inparticularit'sbroadphotoelectronspectrumandrelativelocationoftheelectronicstatesfortheanionandradicalformhaveattractedsignificantresearchbothexperimentallyandtheoretically.[3-6]Oneapproachtotacklethisproblemisabottom-upapproach,startingwithanalysisofthecomponentscomprisingtheGFPchromophore;hydroxybenzylidene-2,3-dimethylimidazolinone(HBDI).Photodetachmentspectrahavebeen obtained for the anion to radical transition of imidazole, bis-imidazoloxy, phenoxide andbisphenoxide. The spectra were calculated from wavepacket propagation using the QUANTICSprogram[7,8],apre-requisiteofwhich is thegenerationofa two-statemodelHamiltonian foreachmolecule.ConstructionoftheseHamiltoniansrequiredthefittingofparameterstopointscalculatedalongthepotentialenergysurfaceusingabinitiomethods.

[1]J.J.vanThor,Chem.Soc.Rev.,2009,38,2935-50.[2]P.J.TongeandS.R.Meech,J.Photochem.Photobiol.AChem.,2009,205,1-11.[3]D.A.HorkeandJ.R.R.Verlet,Phys.Chem.ChemPhys.,2012,14,8511-8515.[4]C.R.S.Mooney,H.H.Fielding,etal.,J.ChemPhys.A,2012,116,7943-7949.[5]Y.Toker,L.H.Anderson,etal.,Phys.Rev.Lett.,2012,109,128101-4.[6]K.B.BravayaandA.I.Krylov,J.Phys.Chem.A.,2013,117,11815-22.[7]G.A.Worth,K.Giri,G.W.Richings,M.H.Beck,A.JäckleandH.-D.Meyer.TheQUANTICSPackage,Version1.1,(2015)[8]M.H.Beck,A.Jäckle,G.A.WorthandH.-D.Meyer.,Phys.Rep.,2000,324,1-105.

40

Poster

Isotopeeffectcalculationsinthesupramolecularage

PhilippeB.WilsonandProf.IanH.Williams

DepartmentofChemistry,UniversityofBath,ClavertonDown,Bath,BA27AY,UKE-mail:[email protected]

Kinetic isotopeeffectsarewidelyusedasexperimentalprobesofchemicalandbiochemical

reactionmechanisms,buthowtheyshouldbeinterpretedforenzymicreactionsremainsproblematic.ComputationalsimulationusingQM/MMmethodsiscapableofprovidingvaluableinsight,butrobustprocedures have not yet been established, and opinion still differs between experimental(1,2) andcomputational(3,4)approachestoenzyme-catalyzedmethyltransfer.Ourrecentstudieshaveindicatedthattheelectrostaticenvironmentaroundasiteofisotopicsubstitutionmayhaveasignificantinfluencethathasnotpreviouslybeentakenintoaccountintheinterpretationofexperimentalkineticisotopeeffects.Wehaveshownthatisotopeeffectsfortransferofamethylcationfromvacuumtoadielectriccontinuumvarydramaticallyovertherangeofdielectricconstantsnormallyassociatedwithenzymeactivesites,(5)andhavearguedthatthecorrectionsforvibrationalanharmonicityonisotopeeffectsarebesttreatedbymeansofscalingofcalculatedharmonicfrequencies.(6)Wehavealsoshownthathydrogen-bondinginteractionsbetweenmethylCHbondsandoxygenatomswithinacage environmentmayhave a significant influenceupon kinetic isotope effects formethyl transferbetweenanucleophileandnucleofuge.Thismayimplyanalternativeexplanation,atleastinpart,forobservedtrendsinkineticisotopeeffectsforenzyme-catalysedmethyltransfer.(1,2).Wesuggestthatourmethodology is applied for the calculationand interpretationof isotopeeffects, anddetail possiblealternativesandapproximationsforfutureworkinthefield.[1]J.ZhangandJ.P.Klinman,JournaloftheAmericanChemicalSociety,2011,133,17134-17137[2]J.Zhang,H.J.Kulik,T.J.MartinezandJ.P.Klinman,ProceedingsoftheNationalAcademyofSciencesoftheUnitedStatesofAmerica,2015,112,7954-7959[3]J.JavierRuizPernia,G.D.RuggieroandI.H.Williams,J.Phys.Org.Chem.,2013,26,1058-1065[4]N.Kanaan,J.J.R.PerniaandI.H.Williams,ChemicalCommunications,2008,DOI:10.1039/b814212b,6114-6116[5]P.B.Wilson,P.J.Weaver,I.R.GreigandI.H.Williams,JournalofPhysicalChemistryB,2015,119,802-809[6]P.B.WilsonandI.H.Williams,MolecularPhysics,2015,113,1704-1711[7]P.B.WilsonandI.H.Williams,AngewChemIntEdit,2016,55,3192-3195.

41

Poster

Aforcefieldfortheaccuratecalculationofthestructureandvibrationalspectroscopyofcarbonmaterials

PriteshTailor,RichardJ.WheatleyandNicholasA.Besley

SchoolofChemistry,UniversityofNottingham,Nottingham,NG72RD

Email:[email protected]

Theaccuratepredictionofthevibrationalspectroscopyofcarbonnanomaterialsisaproblemoffundamental interest and a challenge for computational methods. The capability to compute thevibrational frequencies and associated spectra of these systems accurately can potentially aid theinterpretation and classification of carbon nanotubes (CNT) and graphene in experimentalmeasurementsandallowtherelationshipbetweenthemolecularstructureandtheobservedfeaturestobeexplored.Calculationofthevibrationalspectroscopyofthesematerialsusingquantumchemistrywithinanon-periodic framework is computationally too expensive. An alternative approach is to simplify thedescriptionoftheforce-fieldthroughtheuseofanempiricalpotential.Forsuchmethodstobeofvaluethentheresultingdecreaseincomputationalcostcannotleadtoanunacceptablereductioninaccuracy.HerewepresentafullyempiricalmethodformodelingtheRamanspectroscopyofCNTsandgraphene.The calculations use a purpose built force-field based on the Murrell-Mottram potential [1] incombinationwiththeEmpiricalBondPolarizabilitymodel.AnalyticalfirstandsecondderivativesoftheMurrell-MottramhavebeenimplementedandthepotentialreparameterizedviaaMonte-Carlo“hessianmatching” approach creating a force-field which accurately models the vibrational behavior andspectroscopy of CNTs and graphene. It is shown that the potential accurately models the Ramanspectroscopyofthesesystemsatafractionofthecomputationalcostallowingfortheaccurateatomisticvibrationalanalysisofsystemswithgreaterthan10,000atoms.Subsequently,theRamanspectroscopyofCNTswithdefectsisexplored.

[1]J.N.MurrellandR.E.Mottram,Mol.Phys.,1990,69,571–585.

42

Poster

AnewhybridfunctionalforDensityFunctionalTheoryinspiredbytheUnsoldapproximation

TimWilesandFredManby

BristolUniversitySchoolofChemistry,England


DensityFunctionalTheory(DFT)isasuccessfulab-initiomethodforcalculatingtheelectronicstructureofmolecules.Itssuccessisduetoitslowscalingincomputationalcomplexitywithsystemsize.Theenergyofthemolecule isexpressedasafunctionalof𝜌23 𝐫 , thedensityofthe”Kohn-Shamauxiliarysystem”ateverypointinspace.”Hybrid”functionalsareawidely-usedcorrectionthatcanbeaddedtotheDFTenergytoimproveitsaccuracy.Thesefunctionalsdependonthesingle-particlereduced-densitymatrix𝜌23 𝐫, 𝐫′ ,inadditiontothedensity𝜌23 𝐫 .Wepresentanewhybridfunctionalinspiredbythe”Unsoldapproximation”[1].WeaimtotestthisnewmethodagainstCoupled-ClusterTheorycalculationsoftheelectronicenergyofmolecules.

[1]A.Unsold,Z.Phys.,1927,43,563.

43

Poster

Vibrationalstructuresinthenear-UVelectroniccirculardichroismspectraofproteins

ZhuoLiandJonathanD.Hirst

SchoolofChemistry,UniversityofNottingham,UniversityPark,NottinghamNG72RD,UnitedKingdom


A fully quantitative theory of the relationship between protein conformation and opticalspectroscopywouldfacilitatedeeperinterpretationandinsightsintobiophysicalandsimulationstudiesofproteindynamicsandfolding.Weemploythestate-averagedCASSCFmethodtocalculatevibrationalstructuresoftoluene,p-cresoland3-methylindole,whichrepresentthechromophoresinthearomaticaminoacidsphenylalanine,tyrosineandtryptophan,respectively.TheresultsofthesecalculationsareusedtoincorporatetheFranck-Condoneffectsintomatrixmethodcalculationsoftheelectroniccirculardichroism(CD)spectraofproteins inthenear-ultraviolet.Asetof40proteins,whosestructuresarereportedintheproteindatabank,arecalculatedtoassesstheinfluenceofvibrationalstructuresintheaccuracyofcalculations.Mutantsofvariousproteinsarecalculatedtoillustratetherelationshipbetweenspectrachangesandthestructuraldifferencesinducedbythemutation.ComputedspectraofsomeselectedproteinsfromthedatasetarecomparedwiththecalculationsconsideringtheconformationaldiversitybasedontheavailabilityoftheNMR-determinedproteinstructures.OurcalculationsconsideringvibrationalstructuresofthearomaticchromophoreshaveprovidedsomefurtherinsightintothephysicaloriginsofthenatureofproteinCDspectrainthenear-UV.

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