From:	<buyong -x- at -x- ibmnla.chem.uga.edu>
Date:	Mon, 5 May 1997 21:55:39 -0400 (EDT)
Subject:	Re: CCL:PES Calculation

	I am not sure about what is wrong with your results. If I
am doing this project about bond dissociation, I would:
1. starting from molecule, rather than fragments.
2. Keep the symmetry to be Cs in all calculations.
3. UHF would not work anyway. Minimum level should be Two-Configuration
SCF (TC-SCF),which is equvalent to GVB theory in Gaussain package. CASSCF
should also work, but it is hard to include all reqired orbitals.

=================================================================
Dr. Buyong Ma             buyong()at()ibmnla.chem.uga.edu
Computational Center for Molecular Structure and Design
Department of Chemistry
University of Georgia
Athens, Georgia 30602 USA            Voice (706) 542-2044
=================================================================



On Mon, 5 May 1997, Lin Ping wrote:

> Hi ,everyone,
>
> Does anyone have any suggestion about the calculation of potential
> energy suface in the bond breaking process? I try to break the C-C
> single bond in CH2CH-CN with geometry relaxation, I have tries quite
> some methods such as UHF, CASSCF etc.. Also I have tried to put two
> fragment( Optimized seperately) together and alter the orbital after a
> triplet UHF calculation to make a singlet state and then decrease the
> distance between the two carbon. In the casscf calculation I have
> included 8 electrons and 10 orbitals to make sure to include the C-C
> antibonding orbital. but None of this work properly. I think maybe it is
> the delocalization make the calculation become difficult. By the way, I
> am new in this area, so there are still a lot of things for me to learn.
> Can you give me some suggestions or references in such a calculation?
>
> Also, when using 3-21G and LanL2DZ basis set to calculate a *MoH5
> radical , it is unable to find a optimizated geometry and the SCF
> calculation converged very slowly, especially when doing a DFT
> calculation with LanL2DZ.
>
> Thanks in advance.
>
> LIN Ping
> plin # - at - # chemvx.tamu.edu
>
> --
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