From kessi-: at :-psizi1.psi.ch  Tue Apr  8 09:41:17 1997
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From: kessi ":at:" psizi1.psi.ch (Alain Kessi)
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To: genghis#* at *#darkwing.uoregon.edu, chemistry#* at *#www.ccl.net,
        schiffer #at# h1tw0036.hoechst.com
Subject: Re: CCL:G:geometry optimization methods
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Heinz Schiffer wrote:
> Optimization with Z-matrix coordinates is always the worst that you
> can do, next come cartesian coordinates, and the best are the natural
> internal coordinates of Pulay. Cartesian coordinates are o.k. if you
> have a good initial guess of the Hessian matrix (e.g. computed by
> a less expensive method). See : Jon Baker, Techniques for Geometry
> Optimization : A Comparison of Cartesian and Natural Internal
> Coordinates, J. Comput. Chem. 14(9) (1993) 1085-1100.

You may also want to have a look at our more recent paper

Jon Baker, Alain Kessi and Bernard Delley, The generation and use of
delocalized internal coordinates in geometry optimization, J. Chem. Phys.
105(1) (1996) 192-212.

which shows some trends for much larger systems.

Alain