ISSN:
0020-7608
Keywords:
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Binary electron impact ionization or (e, 2e) spectroscopy has recently been employed to measure molecular orbital momentum distributions in a variety of molecules. Interpretation of the momentum distributions ρ(q) has been facilitated by the use of the wave-function autocorrelation function B(r). In some cases differences in the autocorrelation function of two orbitals may be semiquantitatively interpreted in terms of contour plots of the average and difference of their position-space orbital amplitudes. The σg and σu orbitals of a homonuclear diatomic provide a simple illustration of this point. Calculated and experimental spherically averaged ρ(q) for the predominantly N 2p lone-pair HOMOs of NH3 and CH3NH2 are shown using a ΔB(r) analysis to indicate significant participation of the CH3 hydrogens in the lone-pair orbital of CH3NH2. Although the difference in ρ(q) between the lone pairs of NH3 and CH3NH2 is adequately reproduced by split valence (SV) level ab initio SCFMO calculations the experimental ρ(q) have their maxima at considerably smaller absolute values of q then that obtained from either SV or near Hartree-Fock SCFMO calculations. Experimental and calculated momentum distributions are also presented for the 2t2g HOMO of Cr(CO)6. A ΔB(r) analysis of ρ(q) for this orbital confirms that it has mixed Cr 3d and CO 2π character.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560260844
