Electron momentum distributions of the highest occupied molecular orbital of CF3Br: Delocalization of halogen lone-pair orbitals

摘要

The highest occupied molecular orbital (HOMO) of trifluorobromomethane (CF3Br) is studied by binary (e, 2e) electron momentum spectroscopy. The experimental momentum profile of the HOMO is compared with the Hartree-Fock (HF) and density functional theory (DFT-B3LYP) calculations. The calculated results largely depend on the size of basis sets rather than theoretical methods. Both the HF and DFT calculations using the 6-311++G** basis set give a good explanation to the experiment. Delocalization of halogen lone-pair orbitals in the series molecules CF3X (X= F, Cl, Br) has been investigated.