This bug has been reported to the people at SCM, and they are working at
it.

There is a workaround for the problem, which involves setting up 3 dummy
points,
to which the dihedral angles should relate. It simply involves avoiding
dihedral angles
around 0 or 180 degrees, which seemed to help our similar problems.

I have written a program that automatically converts files into a
suitable Z-matrix format,
which I will be pleased to share with people on this list, if they want
to. However, the program
is currently in development in going from Fortran77 to Fortran90, so the
number of file
formats that can be read is still rather limited.
(in fact, it can handle only 1 format, atom name plus x, y z in
Angstroms)
Still, I think it may satisfied your needs, so please let me know if you
would like to try it.

On Saturday, August 3, 2002, at 12:17 , Rob Deeth wrote:

> For some time, I have avoided Z-matrix geometry optimisations in ADF.
> However, with the latest ADF2002.02 I had high hopes for success.
>
> Unfortunately, when attempting to optimise a molecule with planar
> ligands (imidazoles) using internal coordinates, ADF fails. As far as I
> can see, there are torsion angles which vary from -179 to +179 between
> successive optimisation steps which is then reported as an angle step
> size greater than the default of 10 and so around we go again. At the
> same time, the gradients start going through the roof.
>
> ADF2.3 was nice and stable and RELIABLE. You could shove just about
> anything at it and it would normally converge. However, ADF2.3 does not
> have all the new capabilities which are essential.
>
> This is extremely annoying and a problem which we complained about
> right back when ADF2000 first appeared and yet still seems to be
> present. The inability to perform Z-matrix optimisations or linear
> transits is a serious shortcoming and will eventually force me to
> convert to another program system.
>
> I am copying this to the members of adf-list in the hope that if we all
> make enough noise, fixing the error will become the number one priority.
> I will attach an offending output to a subsequent mail to avoid
> clogging up everyone's mail systems.
>
> Signed Disgruntled in Warwick
>
> Rob Deeth
>
>
> Dr R. J. Deeth
> Department of Chemistry
> University of Warwick
> Ph: +44 (0)24 76523187
> Web: www.chem.warwick.ac.uk/iccg
>
>
>
–––––––––––––––––––––––––––––––––––––
Marcel Swart

Organische en Anorganische Chemie
Faculteit der Exacte Wetenschappen
Vrije Universiteit Amsterdam

De Boelelaan 1083
1081 HV Amsterdam
The Netherlands

F +31-(0)20-4447488
E swart_at_chem.vu.nl
W http://go.to/m.swart
–––––––––––––––––––––––––––––––––––––
Received on 2002-08-03 20:24:11