Subject: Re: MOPAC calculations

From: "Victor Anisimov" <[email-masked]>
Date: Mon, 21 Jun 1999 09:28:50 +0200

Dr Philippe CHAVATTE wrote:

>I encounter some problems with MOPAC geometry optimizations which abort
>because small changes in internal coordinates causing a large change in the
>distance between chemically-bound atoms.
>I would appreciate any suggestion on how to renumber the atoms.

Try next options:

1) If you use EF method in geometry optimization you can restrict geometry
deviations by keywords
DDMAX=0.01 DDMIN=0.001 LET

2) Try to add keyword XYZ and perform optimization in Cartesian coordinates.

3) One can combine both mentioned methods.

Victor.

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Victor Anisimov, PhD, Software Researcher - Computational Chemistry
FQS Poland, Palac Pugetow, ul. Starowislna 13-15, 31-038 Krakow, Poland
Email: [email-masked]  Tel.(+48 12) 429 4345  Fax(+48 12) 429 6124
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