ISSN:
0020-7608
Schlagwort(e):
Computational Chemistry and Molecular Modeling
;
Atomic, Molecular and Optical Physics
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The 3-21G basis set shares with its older cousin, the 4-31G basis set, a tendency to overestimate valence angles at nitrogen atoms and to underestimate seriously barriers to inversion at such atoms. The 6-31G* basis set generally yields greatly improved results in these respects. It is here shown that, for a variety of molecules, supplementation of the 3-21G basis set at three- or two-coordinate nitrogen atoms with a set of six d-functions having exponent 1.0 leads to optimized geometries and inversion barriers at such nitrogen centers in good agreement with results obtained with the 6-31G* basis set. This supplemented basis set, designated as 3-21G(N*), also leads to calculated vibrational frequencies in good agreement with those calculated with the 6-31G* basis set. The 3-21G(N*) basis set offers an economical alternative to the 6-31G* basis set, particularly for molecules containing several first-row atoms other than nitrogen.
Zusätzliches Material:
2 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/qua.560310310
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