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Semiempirical versus ab Initio Calculations of Molecular Properties. I. Diamagnetic Susceptibilities and Quadrupole Moments in Some Medium Size Molecules

A . Graovac ; Theoreticai Chemistry Group, »Ruder Boskovic« Institute, 41001 Zagreb, Yugoslavia
Z. B. Maksić ; Theoreticai Chemistry Group, »Ruder Boskovic« Institute, 41001 Zagreb, Yugoslavia
K. Rupnik ; Theoreticai Chemistry Group, »Ruder Boskovic« Institute, 41001 Zagreb, Yugoslavia
A. Veseli ; Department of Physics, Faculty of Natural Sciences, 38000 Pristina, Yugoslavia

Sažetak

The self-consistent charge molecular orbital (SCC-MO) method
was applied to a number of medium size molecules involving atoms
exhibiting large differences in electronegativity and possessing one
or more lone pairs. The quality of the wave functions thus obtained
was applied to a number of medium size molecules involving atoms
calculated by a rigorous treatment of the operators x2, y2, and z2•
The SCC quadrupole moments can be favourably compared with the
ab initio results of Snyder and Basch obtained by the use of a
Gaussian double zeta basis set. The present results provide additional
justification of the sec method, which has apparent advantages
over the methods based on the ZDO approximation. Some difficulties
encountered in the treatment of pi-electrons are discussed and
suggestions for their remedy are given. The second moments
calculated by the application of a simple additivity formula (Z. B.
Maksic and J. E. Bloor, Chem. Phys. Lett., 13 (1972) 571; J. Phys.
Chem., 77 (1973) 1520) and the related diamagnetic susceptibilities
are in very good agreement with the ab initio values.

Ključne riječi

Hrčak ID:

196123

URI

https://hrcak.srce.hr/196123

Datum izdavanja:

26.4.1978.

Posjeta: 703 *