Vibrational and distorted-wave effects on the highest occupied molecular orbital electronics structure of tetrachloromethane

Abstract

In this work, we study the valence orbital momentum profiles of tetrachloromethane (CCl4) performed with binary (e, 2e) measurements at the impact energies of about 600 and 1200 eV with higher energy-resolution of Δε∼0.7 eV. The experimental momentum profiles for the molecular orbitals 2t1,7t2,2e,6t2, and 6a1 are obtained and compared with calculations under the plane-wave impulse approximation. The calculations at the equilibrium geometry of CCl4 show generally good agreement with the experimental momentum profiles except for the low momentum range of 2t1 and 2e which is considerable lower than the experiment. The experimental momentum profile shows dynamic dependencies on the impact energies which is ascribed to the distorted-wave effects. Further calculation considering molecular vibrations for the 2t1 highest occupied molecular orbital (HOMO) shows a better agreement with experiment than the equilibrium calculation, indicating the important role of nuclear motions on the HOMO electronic structure of CCl4.