Subject: How to get different values of the terms contributing to the HF and DFT orbital energies?? (Gaussian)

From: "Kiniu WONG \(Kin-Yiu\)" <[email-masked]>
Date: Sat, 10 Aug 2002 22:15:22 -0400

Dear all CCLers,

    Both Hartree-Fock (HF) and Density Functional Theory (DFT) orbital
energies are obtained by the diagonalization of the following similar
equation:

    (T + N + C + XC) Psi = energy * Psi,

where T is the kinetic energy operator, N is the nuclear attraction energy
operator, C is the operator of columb repulsion energy among electrons and
XC is the operator of the exchange energy among electrons.

My question is:
    How to get the values of <T>, <N>, <C> and <XC> from Gaussian?  That's
the expectation values of T, N, C and XC with respect to this particular
orbital wavefunction Psi, e.g.  Integrate[Psi N Psi] over one electron
volume???  Is it true that I can obtain these values by some setting of
IOps?

    I know that I may be able to obtain the values of <T> and <N> by the
following methods:

    1.  Generate two cube files of (T Psi) and (N Psi).  The keywords are
"laplacian" and "potential".
    2.  Generate cube file of Psi.
    3.  Obtain <T> and <N> by some manipulation of these cube files by
CubeMan.

However, I don't know how I can get <C> and <XC> by "Cube".  Moreover, I
would prefer to obtain all these expectation values analytically instead of
numerically.  So any suggestions?  Thank you very much in advance!

Wishes,
Kiniu
----

Kiniu WONG (Kin-Yiu)
Graduate Student
Department of Physics
The Ohio State University
USA
Primary Email:   [email-masked]
Permanent Email:   [email-masked]