Pure&Appl.Chem.,Vol.68,No.2,pp.387-456,1996.PrintedinGreatBritain.INTERNATIONALUNIONOFPUREANDAPPLIEDCHEMISTRYPHYSICALCHEMISTRYDIVISIONWORKINGPARTYONTHEORETICALANDCOMPUTATIONALCHEMISTRYACRONYMSUSEDINTHEORETICALCHEMISTRYPreparedforpublicationbytheWorkingPartyconsistingofR.D.BROWN*(Australia,Chiman);J.E.BOWS(USA);R.HILDERBRANDT(USA);K.LIM(Australia);I.M.MILLS(UK);E.NIKITIN(Russia);M.H.PALMER(UK).Thefocalpointtowhichtosendcommentsandsuggestionsisthecoordinatoroftheproject:RONALDD.BROWNChemistryDepartment,MonashUniversity,Clayton,Victoria3168,Australia.Responsesbye-mailwouldbeparticularlyappreciated,thenumberbeing:rdbrown@vaxc.cc.monash.edu.auanotheralternativeisfaxat:+61399054597AcronymsusedintheoreticalchemistrysynogsisAnalphabeticlistofacronymsusedintheoreticalchemistryispresented.Someexplanatoryreferenceshavebeenaddedtomakeacronymsbetterunderstandablebutstillmoreareneeded.Criticalcomments,additionalreferences,etc.arerequested.INTRODUC'IIONTheIUPACWorkingPartyonTheoreticalChemistrywaspersuaded,bydiscussionwithcolleagues,thatthecompilationofalistofacronymsusedintheoreticalchemistrywouldbeausefulcontribution.InitiallistsofacronymsdrawnupbyseveralmembersoftheworkingpartyhavebeenaugmentedbytheprovisionofasubstantiallistbyChemicalAbstractService(seefootnotebelow).TheworkingpartyisparticularlygratefultoCASforthisgeneroushelp.Itsoonbecameapparentthatmanyoftheacronmsneededmorethanmerespellingouttomakethemunderstandableandsowehaveaddedexpranatoryreferencestomanyofthem.Atpresentonlyabout20%oftheacronymsarcaccompaniedbyexplanatoryreferencesbutwejudgethatthereistheneedformanymoretobeadded.HoweverthisISamajortaskandnoonepersonisabletoglikealltherefereacesrequired.WearethereforeseekingthehelpofcolleaguestoprovidemPitionalreferences.Oneofourpurposesinpublishingthelistatpresentistostimulateinterest,criticalcommentsand,especiallysuggestionsforfurtherexplanatoryreferences.PleasenotethatwepreferGxpIanatQryreferencesratherthanthehistoricalf