ISSN:
0192-8651
Schlagwort(e):
Computational Chemistry and Molecular Modeling
;
Biochemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Informatik
Notizen:
New estimates of Hartree-Fock limit energies (ERHF) for selected AH and AHn hydrides, diatomic and linear polyatomic molecules have been made utilizing ESCF values recently reported in the literature for HF, N2, CO, NH3, and CH4 which are very close to the respective limits. These new values have been used to investigate the applicability of Ermler and Kern's procedure for estimating ERHF: i.e., a factor f is first evaluated from data for reference molecules, where f = ERHF/ESCF, which is then used with ESCF values for other molecules to obtain their ERHF values. f has been evaluated for three groups of reference molecules—HF, H2O, NH3, CH4, N2, and CO; CH4, C2H2, C2H4, and C2H6; and C2H2, HCN, and N2—utilizing ESCF data in the literature for many Gaussian-type orbital (GTO) basis sets together with some new values calculated at the (9,5,1) to (13,8,2) levels. Trends in the variation of f within each group of reference molecules from one basis set to another, and the trends in f from one group of reference molecules to another, are discussed in detail. To minimize the influence of these effects in an ERHF estimate it is recommended that the f value should be derived from reference molecules which possess a similar combination of structural features, i.e., bonded hydrogen, single, double, or triple bonds, and the number of lone-pair electrons. Further calculations show that an f value based on data for closed-shell molecules is not applicable to open-shell species.
Zusätzliches Material:
9 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jcc.540020314
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