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 theoretical MDs were calculated using a plane wave impulse approximation (PWIA) model for the reaction mechanism and density functional theory (DFT) for the wave function. Seven basis sets, at the local density approximation (LDA) level and, additionally, incorporating nonlocal correlation functional corrections, were studied. The sensitivity of the level of agreement between the experimental and theoretical MDs to the nonlocal corrections is considered. A critical comparison between the experimental and theoretical MDs allows us to determine the "optimum" wave function from our basis sets. This wave function is then used to derive butadiene's chemically interesting molecular properties, which are subsequently compared to the results of other workers. The sensitivity of the derived molecular property information to the nonlocal correlation functional corrections is also examined.