On the Evaluation Overlap Integrals with the Same and Different Screening Parameters Over Slater Type Orbitals via the Fourier-Transform Method

2005 ◽  
Vol 43 (1) ◽  
pp. 151-158 ◽  
Author(s):  
M Yavuz ◽  
N Yükçü ◽  
E Öztekin ◽  
H Yilmaz ◽  
S Döndür
2004 ◽  
Vol 03 (02) ◽  
pp. 257-267 ◽  
Author(s):  
LILIAN BERLU

In previous work,1 we presented a one center two range expansion method for the evaluation of the two-center overlap-like quantum similarity integrals over Slater type orbitals which are four orbitals overlap integrals. In this work, to improve the accuracy and to reduce the calculation times, the above integrals are developed using the Fourier transform approach and the so-called B functions. With the help of angular momentum selection rules, two-center overlap-like quantum similarity integrals are expressed as combinations of usual overlap integrals (e.g. two-orbitals) which could be evaluated very accurately using the Fourier transform method combinated with B functions.


2005 ◽  
Vol 04 (03) ◽  
pp. 787-801 ◽  
Author(s):  
LILIAN BERLU ◽  
HASSAN SAFOUHI

Molecular overlap-like quantum similarity measurements imply the evaluation of overlap integrals of two molecular electronic densities related by the Dirac delta function. When the electronic densities are expanded over atomic orbitals using the usual LCAO (Linear Combination of Atomic Orbitals) scheme, overlap-like quantum similarity integrals could be expressed as a linear combination of four-center overlap integrals. In previous works, we showed that the one-center two-range expansion method leads to very complicated analytic expressions for three- and four-center terms. This is why its use has been prevented even for two-center integrals. We also showed that the use of the Fourier transform approach, combined with the so-called B functions, leads to great simplifications in both analytical and numerical development of overlap-like quantum similarity integrals over Slater type functions. In this work, a unified analytical treatment of multicenter overlap-like quantum similarity integrals over Slater type functions is described. The Fourier transform and nonlinear transformation methods are used. The numerical results section shows that the approach described in the present work can be applied to two-, three- and four-center integrals whatever nucleus positions might be.


1997 ◽  
Vol 30 (24) ◽  
pp. 3296-3300 ◽  
Author(s):  
M Li ◽  
M O Möller ◽  
H R Reß ◽  
W Faschinger ◽  
G Landwehr

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