From owner-nwchem-users  Mon May  7 01:53:10 2001
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Date: Mon, 07 May 2001 10:32:31 +0200
From: Rochus Schmid <rochus.schmid@ch.tum.de>
Subject: MECP search
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Hello nwchem pros,

I am quite new to NWChem but very happy with it.

In a research project I have to locate the minimum energy crossing point
for the singlet to the triplet surface of a molecule. I have done this
already using turbomole and some python code (which I use frequently).
turbomole has seperate executables for scf and gradient and I just ran
seperate jobs in two directories (for s and t) extracted the gradients
from the output and did the MECP search with a "handmade" BFGS-optimzer
in python.

Now I would like to do a similar thing with NWChem using the python
extension. From the tutorials (especially the BSSE-script) I can see how
to "switch" between geometries in the database. However, it is not yet
clear to me if it is possible to switch between two sets of MO-vecs (one
closed shell, the other open shell) for the same geometry, to converge
and grep the gradient somehow.

(The thing I want to do can be found in:
"The singlet and triplet states of phenyl cation. A hybrid approach for
locating minimum energy crossing points between non-interacting
potential energy surfaces", J. N. Harvey, M. Aschi, H. Schwarz, W. Koch,
Theor. Chem. Acc. (1998) 99, 95-99.)

I would very happy about any sort of help/pointer/hint from the
nwchem-community (or the developers :-).
Thanx in advance,

Rochus

--

Dr. Rochus Schmid
Technische Universität München
Lehrstuhl f. Anorganische Chemie
Lichtenbergstrasse 4, 85747 Garching

Tel.    ++49 89 2891 3174
Fax.    ++49 89 2891 3473
Email   rochus.schmid@ch.tum.de