An investigation of the HOMO frontier orbital electron density distributions of NH3, the methylamines and NF3 using DFT and electron momentum spectroscopy Original Research Article

Density functional theory (DFT: B3LYP and B3PW91) and Hartree–Fock (HF) calculations using large, saturated and diffuse basis sets are compared with earlier reported highest occupied molecular orbital (HOMO) electron momentum density distributions for NH3, CH3NH2, (CH3)2NH, (CH3)3N and NF3 [Chem. Phys. Lett. 137 (1987) 573; Chem. Phys. 123 (1988) 51], measured using electron momentum spectroscopy. Very good quantitative agreement is obtained between the DFT calculations and experiment, in contrast to the rather poor modeling provided by the simpler basis set HF calculations reported in the original studies. The present work demonstrates the need to include dynamic electron correlation in order to correctly model these frontier orbital (HOMO) electron densities.