[Pw_forum] difference from the output of dynmat.x and Phonon dyn file

[Paolo Giannozzi]

On Thursday 12 January 2006 04:59, W. YU wrote:

> I found the difference between the two outputs are not
> connected by a factor of M^{-1/2}). For some modes they
> are almost the same, such as modes 12. But for others 
> they differ a lot, such as mode 4. The subtle difference in 
> mode 4 may come from the accoustic sum rule.

low-lying modes with low energy tend to have a sizable admixture
of the zero-ferquency translational mode, so it is quite likely that
upon application of the acoustic sum rule they look somewhat 
different. 

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy