[CPMD-list] problem with geometry optimisation

[Axel Kohlmeyer]

> 
> which is not very consistent with previous calculations particularly
> around 500cm-1. Any ideas?

the reproducability of spectra depends a lot on what you are
comparing to. particularly, when looking at weak(er) interactions.

for example, i'm currently looking at an example where the 
energy minimum is only about 0.5 kcal/mol deep. the difference 
in results between methods or functionals and basis set size
are very large...

i would suggest to see if there is a recognizable consistency
amongst frequencies/vibrations that are 'off' and perhaps start
playing with parameters related to the affected atoms and/or
replace the pseudopotentials.

cheers,
   axel.


-- 
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Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
   Center for Molecular Modeling   --   University of Pennsylvania
Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
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