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1、Self-diffusionCoefficientModelBasedonActivationEnergyandFreeVolumeCHINESEJOURNALOFCHEMICALPHYSICSARTICLEVOLUME19,NUMBER6DECEMBER27,2006Self-diffusionCoefficientModelBasedonActivationEnergyandFreeVolumeXiao—yongYin,Hal—huaSongSchoolofChemicalEngineering,TianjinUni
2、versity,Tianjin300072,China(Dated:ReceivedonFebruary22,2006;AcceptedonAugust儿,2006)Anewmodelforself-diffusioncoefficientswasproposedbasedOilboththeconceptsofmolecularfreevolumeandactivationenergy.TheunMlownparametersofthismodelwereclearlydefinedandcomparedwiththe
3、Chapman—EnskogmodelAtthesametimeanewmethodforcalculatingactivationenergywandevisedandappliedtothenewmode1.Inaddition,thefreevolumewasdefinedbyimplementingthegenericvanderWaalsequationofstate,theradialdistributionfunctionofwhichwasobtainedbyusintheMorsali—Goharsha
4、diempiricMformula,Underthesameconditions,thenewmodelwasbetterthantheoriginalfreevo】t1inemnde1Keywords:l~~eevolume,Poter,tialenergybarrier,Self-diffusioncoefficient,PaircorrelationfunctionI.1NTRODUCTIONIntilestudyoftransportprocessesandotherdynam—icalthermophysica
5、lpropertiesofliquids,selgdiffusioncoe币cientsareimportant.becauseselgdiflusionofpar—ticlessetstilebasictiilleandspatialscalesofdynamicevolutionofthesysteln.Moreover,theviscosityandthermalconductivityinaybeexpressedintermsoftilesel5diflusioncoe卅cient.However.tileth
6、eoreticcalcu-lationofthemolecularselgdiflusioncoefficientsofgasesandliqllidsisnotonlydifficultand1aboriousbutalsotimeconsulning.Tobesufficientlyaccurate.theirCOrn—putationgenerallyhastobecarriedoutbygleansofcomputersimulationmethods—typically.amoleculardy—namics(
7、MD)simulationmethodf11.Ifonecalculatesthediffusioncoe币cientsbyusingMD.onewillobtainiteitherbyusingtheGreen—Kuboformula.=1N..(-)ortheEinsteinforinula_ⅣD=∑((一))—--—1i1(1)HoweVer.thismethodistimeconsumingbecause/—————-÷———————',(t)(0))'decaysalongwithtandthisalgebra
8、iclong—timetailmakesasubstantialCOlltri—butiontothediffusioncoefficientf21.Meanwhile((r()一7?(0)).)hasalmostthesamecharacteristicsasAuthortowhomcorrespondencexi
