文档介绍：计算凝聚态物理凝聚态物质的数值模拟方法(5)分子模型,分子动力学方法马红孺./Ccmp/-10-21上海交通大学理论物理研究所马红孺分子模型Molecularsystems:Inmostcasestheinteractionpartcanbeapproximatedbypairinteractions:OnefamousexampleistheLennard-Jonespotential2003-10-21上海交通大学理论物理研究所马红孺分子模型Averyimportantquantityinstatisticalmechanicsisthepaircorrelationfunctiong(r,r0),definedaswhereItmayalsobewrittenas2003-10-(r).Theg(r,r0)(r)tendsto1,hetotalcorrelationfunctionTheFouriertransformoftheabovefunctiongivesthestaticstructurefunction(orstructurefactor)2003-10-ponentofdensityfluctuations[Thedensityisdefinedas:,andthedensityfluctuationis:,ponentis:]2003-10-21上海交通大学理论物理研究所马红孺分子模型当体积趋于无限时,-10-,forexampletheenergyinNVTensembleisThepressureis2003-10-pressibilityThisexpressioncanbederivedfromthefluctuationsofparticlenumbersSinceso2003-10-21上海交通大学理论物理研究所马红孺分子模型Ontheotherhand,,Forsystemsatequilibriumthetimecorrelationfunctionisafunctionofthetimedifferenceonlyandcanbewrittenas2003-10-21上海交通大学理论物理研究所马红孺分子模型ThevelocityautocorrelationfunctionoftheithparticleisThiscanbederivedfromthedefinitionrelation(wewillbacktothispoint).