[Pw_forum] frequency of NO molecule

Paolo Giannozzi giannozz at nest.sns.it
Thu Sep 7 17:31:34 CEST 2006

On Thursday 07 September 2006 16:01, Axel Kohlmeyer wrote:
> how about including several atoms in the neighborhood of the 
> adsorbed molecule? this is how it works in CPMD: you pick an
> atom (or pick a reference coordinate) and set a radius and then 
> do the vibrational analysis for those atoms and keep the rest fixed. 
> this way you include at least the contributions from the near 
> neighbors, have the rest as 'static background', and still save
> a lot of (cpu) time. 

the problem I see in this approach is that the vibrations of 
surface atoms close to the adsorbed molecule may be 
strongly correlated to vibrations of other atoms in the 
surface; i.e., taking only a few surface atoms close to 
the molecule will produce rather bogus displacement
patterns for those atoms. 

Paolo Giannozzi             Phone:   +39/050-509876
DEMOCRITOS and SNS          Fax:     +39/050-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy

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