Subject: gradients of overlap integrals

From: "Eric R. Bittner" <[email-masked]>
Date: Wed, 29 Jul 1998 10:57:03 -0500

Greatings CCL'ers

We need to calculate the gradient of an overlap integral
between tight-binding basis functions. 
i.e. we need
d/dx <psi_a | psi_b>  

I believe these are called "Pulay forces" but I have not been able
to dig up a reference to that effect.
Is there a standard reference or technique for computing these?

Thanks,
ERB

-- 
Eric R. Bittner                 [email-masked]
Dept. of Chemistry              ph: 713-743-2775
University of Houston          fax: 713-743-2709
Houston TX 77204              http://k2.chem.uh.edu/bittner/
 "confutatis maledictis, flammis acribus addictis..."