Modifiye edilmiş örtme ve nükleer-çekim integrallerinin hesaplanması / Selda Özcan; Danışman Metin Yavuz.

Abstract

For examination of molecular structures, one of the approximate methods used in molecular orbital theory is Hartree-Fock-Roothaan (HFR) method. In using this method a large number of molecular integrals occur. The calculation of this molecular integrals over Slater type orbitals (STO) has recently gained a renewed interest. In this study, first definitions and basic formulas for molecular integrals were given. Then modified overlap integrals were expressed through the basic coefficients and overlap integrals with the same screening parameters of STO's. Secondly three- and two-center nuclear-attraction integrals of STO's were presented by using modified overlap integrals. Specially two-center nuclear-attraction integrals were expressed in terms of the overlap integrals depent on only one quantum sets: (). For this expressions the computer programs using Turbo Pascal 7.0 language were constructed. Finally, the modified overlap and nuclear-attraction integrals over STO's were calculated for extremely large quantum numbers using Gegenbauer coefficients and basic overlap integrals. It was seen that the accuracy of the results was quite high for the principal quantum numbers of Slater functions and for arbitrary values of internuclear distances and screening constants of atomic orbitals.