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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. June 2005, Volume 4, Number 6, 413-422 |
Numerical Evaluation of Two-Center Overlap Integrals Over Slater-Type
Orbitals and Convergence Properties
Hassan Safouhi and Ahmed Bouferguene
Internet Electron. J. Mol. Des. 2005, 4, 413-422
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Abstract:
Among the molecular integrals, the two-center overlap integrals
play a major role in any accurate molecular structure calculation.
They are central to the calculation of multicenter overlap integrals
when using the series expansion formulae for Slater type functions
about a new center. Consequently, these integrals require an
accurate and fast numerical evaluation. Recently, we showed that
these integrals are suitable to apply the nonlinear D
transformation of Sidi, which is shown to be highly efficient in
improving convergence of highly oscillatory integrals. In this
work, we present an algorithm for a numerical evaluation of the
molecular integrals under consideration over STOs. Convergence
properties in the numerical evaluation of these molecular integrals
are discussed. It is now shown that the approximation obtained
using the nonlinear D transformation converges to the exact value
of the integral without any constraint. Numerical results are
obtained for two-center overlap integrals over Slater type orbitals
with HCN, C2H2, BH3
and CH4 molecules. Comparisons with
results obtained using the ACJU code developed by Homeier et al.
are presented. Numerical results from the literature were also
reproduced using the algorithm described in the present work. The
results obtained in this work illustrate the efficiency of the
algorithm based on the nonlinear D transformation, which will
lead to a highly accurate algorithm for the numerical evaluation of
the integrals under consideration.
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