microscopic simulations in physics

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1、MicroscopicsimulationsinphysicsD.M.CeperleyNationalCenterforSupercomputerApplications,DepartmentofPhysics,UniversityofIllinoisatUrbana-Champaign,Urbana,Illinois61801[S0034-6861(99)01802-4]I.INTRODUCTIONComputationalphysicshasbeensaidtoconstituteathirdwayofdoingphysics,comparabletotheoryandIn1820,La

2、placespeculatedondeterminingthecon-experiment.Whatistheroleoftheoryorsimulationinsequencesofphysicallaws:physicstoday?Howcansimulationsaidinprovidingun-Anintelligentbeingwho,atagivenmoment,derstandingofaphysicalsystem?Whynotjustmeasureknowsalltheforcesthatcausenaturetomoveandpropertiesinthelaborato

3、ry?Oneansweristhatsimula-thepositionsoftheobjectsthatitismadefrom,iftioncangivereliablepredictionswhenexperimentsarealsoitispowerfulenoughtoanalyzethisdata,wouldnotpossible,verydif®cult,orsimplyexpensive.SomehavedescribedinthesameformulathemovementsofexamplesofsuchquestionsareWhatisthebehaviorofthe

4、largestbodiesoftheuniverseandthoseofthehydrogenandotherelementsunderconditionsequiva-lightestatoms.Althoughscienti®cresearchsteadilylenttotheinteriorofaplanetorstar?Howdophaseapproachestheabilitiesofthisintelligentbeing,com-transitionschangeingoingfromtwotothreetofourpletepredictionwillalwaysremain

5、in®nitelyfaraway.dimensions?IsthestandardmodelofQCDcorrect?PartofthereasonforthepervasivenessofsimulationsHisintuitionaboutcompletepredictabilityhasbeenisthattheycanscaleupwiththeincreaseofcomputerborneout:ingeneral,dynamicsischaotic,thusmakingpower;computerspeedandmemoryhavebeengrowinglong-rangefo

6、recastsunreliablebecauseoftheirsensitiv-geometricallyoverthelast5decadeswithadoublingitytoinitialconditions.timeofroughly18months(Moore'slaw).TheearliestThequestionremainswhetheraveragepropertiessimulationsinvolved32particles;nowonecandohun-suchasthosethatariseinstatisticalmechanicsandther-dredsofm

7、illionsofparticles.Theincreaseinhardwaremodynamicsmaybepredictablefrom®rstprinciples.speedwillcontinueforatleastanotherdecade,andim-Shortlyaftertheformulationofquantummechanicsprovementsinalgorithmswillhope