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1、ImprovedwavefunctionsforquantumMonteCarloPriyankaSethCorpusChristiCollege,CambridgeDissertationsubmittedforthedegreeofDoctorofPhilosophyattheUniversityofCambridgeAugust2012Tomum,dad,ìÉìÉandthememoryofêÉ.PrefaceThisdissertationdescribesworkcarriedoutbetweenOctober
2、2008andAugust2012intheTheoryofCondensedMattergroupattheCavendishLaboratory,CambridgeunderthesupervisionofProf.R.J.Needs.Thefollowingchaptersareincludedinworkthathaseitherbeenpublishedoristobepublished:Chapter3:P.Seth,P.LopezRosandR.J.Needs,QuantumMonteCarlost
3、udyoftherst-rowatomsandions",J.Chem.Phys.134,084105(2011).Chapter4:P.LopezRos,P.Seth,N.D.DrummondandR.J.Needs,FrameworkforconstructinggenericJastrowcorrelationfactors",Phys.Rev.E86,036703(2012).Thisdissertationistheresultofmyownworkandincludesnothingwhichist
4、heoutcomeofworkdoneincollaborationwithothers,exceptwherespecicallyindicatedinthetext.Thisdissertationhasnotbeensubmittedinwholeorinpartforanyotherdegreeordiplomaatthisoranyotheruniversity.Thisdissertationdoesnotexceedthewordlimitof60,000words.PriyankaSethCambrid
5、ge,August2012iAbstractQuantumMonteCarlo(QMC)methodscanyieldhighlyaccurateenergiesforcorrelatedquantumsystems.QMCcalculationsbasedonmany-bodywavefunc-tionsareconsiderablymoreaccuratethandensityfunctionaltheorymethods,andtheiraccuracyrivalsthatofthemostsophisticate
6、dquantumchemistrymethods.Thisthe-sisisconcernedwiththedevelopmentofimprovedwavefunctionformsandtheiruseinperforminghighly-accuratequantumMonteCarlocalculations.All-electronvariationalanddiusionMonteCarlo(VMCandDMC)calculationsareperformedfortherst-rowatomsandsi
7、ngly-positiveions.Over98%ofthecorrelationenergyisretrievedattheVMClevelandover99%attheDMClevelforalltheatomsandions.Theirrstionizationpotentialsarecalculatedwithinchemicalaccuracy.Scalarrelativisticcorrectionstotheenergies,mass-polarizationterms,andone-andtwo-el
8、ectronexpectationvaluesarealsoevaluated.Aformfortheelectronandintraculedensitiesispresentedandtstothisformareperformed.TypicalJastrowfactorsusedinquantumMonte