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:
Interior electron densities are divided from exterior electron densities (EED), when an effective boundary is introduced. The EED concept was used to study the quality of wavefunction tails; the basis-set dependence of ab initio MO for NH3 was studied from EED. The EED for the nonbonding orbital (3a1) increases dramatically with the size of basis sets, whereas that for the bonding orbital (1e) shows saturation even at the double zeta class. Although inclusion of polarization functions always gives the better total energy the EED (3a1) may either increase or decrease or decrease depending on the choice of the smaller or the larger exponents. The conventional choice of the polarization functions for 6-311G* and 6-311G* was found to yield worse wavefunction tails than the case of 6-311G. Much better results were obtained with the more diffuse polarization functions. The (11s7p)/[5s4p] set designed for Rydberg states as well as the 6-311 + G set proposed for negative ions gave excellent results comparable to the case of the near Hartree-Fock calculation with 56 CGTO. Considerable improvements were also achieved for 4-31G and 6-311G sets, when the exponent for the outermost s-type function was modified. The largest EED (3a1) gave the best agreement with the experimental ratio of EED's derived from Penning ionization electron spectroscopy.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/qua.560290410
