Weinvestigatetheperiodhalvingofpersistentcurrents(PCs)ofnon-interactingelectronsinisolatedmesoscopicMobiusladderswithoutdisorder,piercedbyAharonov-Bohmflux.Themechanismsoftheperiodhalvingeffectdependontheparityofthenumberofelectronsaswellasontheinterchainhopping.AlthoughthedataofPCsinmesoscopicsystemsaresamplespecific,somesimplerulesarefoundinthecanonicalensembleaverage,forexample,alltheoddharmonicsofthePCsdisappearandthesignalsofevenharmonicsarenon-negative.
