MOMENTUM DISTRIBUTIONS AND MOLECULAR PROPERTY INFORMATION FOR TRANS 1,3-BUTADIENE - AN ELECTRON MOMENTUM SPECTROSCOPY AND DENSITY-FUNCTIONAL THEORY INVESTIGATION

The technique of electron momentum spectroscopy (EMS) has been used to measure orbital momentum distributions (MDs) for the complete valence electronic structure of trans 1,3 butadiene. The corresponding theore tical MDs were calculated using a plane wave impulse approximation (PW IA) model for the reaction mechanism and density functional theory (DF T) for the wave function. Seven basis sets, at the local density appro ximation (LDA) level and, additionally, incorporating nonlocal correla tion functional corrections, were studied. The sensitivity of the leve l of agreement between the experimental and theoretical MDs to the non local corrections is considered. A critical comparison between the exp erimental and theoretical MDs allows us to determine the ''optimum'' w ave function from our basis sets. This wave function is then used to d erive butadiene's chemically interesting molecular properties, which a re subsequently compared to the results of other workers. The sensitiv ity of the derived molecular property information to the nonlocal corr elation functional corrections is also examined. (C) 1998 American Ins titute of Physics.