Subject: SUMMARY for: Code for overlapping STOs

From: Daniel Katz <[email-masked]>
Date: Tue, 28 Oct 1997 16:26:39 -0800 (PST)

On Thu, 16 Oct 1997, I wrote:

> 
> IS there a free and non obscure piece of code (preferably C) for 
> calculating the overlap integrals between two Slater-Type-Orbitals (single 
> zeta, radial part, angular parts are real spherical harmonics for s,p, and 
> d)?  I have the MOPAC FORTRAN routines, but they are not clear to me.
> 
> Thanks in advance.
> 
> Daniel J. Katz
> UC Davis, Dept. of Chemistry
> [email-masked]
> 

I got two replies, one from Ernst-Udo Wallenborn and one from Frederic A. 
Van-Catledge.  Both sent code, for which I am very grateful.  In addition 
Frederic wrote on the general method:

1.  The key to getting good STO overlaps is having good routines/functions
for calculating the A & B auxiliary integrals,... *especially* the B's.

 ... [my elipsis here] 

If one has that, the problem reduces to recasting the formal integral 
>from local cartesian coordinates into confocla elliptical coordinates, i.e.,
        I(Xa, Ya, Za, Xb, Yb, Zb) --> I(mu, nu, phi)
The rest, as they say, is a simple mater of algebra.

Daniel J. Katz
University of California at Davis
[email-masked]