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

Density functional theory (DFT: B3LYP and B3PW91) and Hartree-Fock (HF) cal culations using large, saturated and diffuse basis sets are compared with e arlier reported highest occupied molecular orbital (HOMO) electron momentum density distributions for NH3, CH3NH2. (CH2)(2)NH, (CH3)(3)N and NF3 [Chem . Phys. Lett. 137 (1987) 573; Chem. Phys. 123 (1988) 51], measured using el ectron 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 dynami c electron correlation in order to correctly model these frontier orbital ( HOMO) electron densities. (C) 2001 Elsevier Science B.V. All rights reserve d.