Subject: Re: CCL:geom. optimiz. of macrolide

From: Anatoli Korkin <[email-masked]>
Date: Fri, 15 Aug 1997 11:36:44 -0400 (EDT)

Natalie,

There can be many reasons why your structure does not converge. It is hard
to give general advices witout seeing the case. It is the same as asking for
a diagnosis by telephone tellling that someone has a fiver.

One simple reason can be two close conformations or two close electronic
states which oscilate. Series of separate partial optimization of parameters
which have different force constants (e.g. optimization of dihedral angles
separately from others) may help. Other suggestion is using different 
algorithms for optimizations, modifying maimal step in optimization, etc.
Even a better definition of z-matrix can be crucial.

If this does not help, you need to see a doctor :-)

Good luck,

Anatoli

> 
> Dear all,
> I am trying to optimiza the geometry of a macrolide with the s-e method AM1.
> The geometry doesn't reach a convergence...Is there someone with any
> experience with such of problem?
> Thanks for helpinf
> Nathalie
> 
> 
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