[CPMD-list] vibrational frequencies from MD tragectories

[Robert Williams]

Dear CPMD users,

Has anyone calculated vibrational frequencies from CPMD MD
trajectories using principal component analysis (singular value
decomposition)?   It appears that it may give better results than
those obtained using fourier transforms of autocorrelation functions:
http://cheminfo.chem.ou.edu/~raw/methods.html#vibrations

It is still not clear to me how to obtain anharmonic frequencies from MD
trajectory files.  I've read several papers by Putrino, Bernasconi,
Silvestrelli, and M. Parrinello, and it appears that it is necessary
to write code to calculate an autocorrelation function on some 
information in
the trajectory file.  I have the fourier transform program provided by
Axel.   Has no-one contributed other code or a "howto" that can make
this easier?  There are definitely barriers here for the non-specialist.
There are only 24 hours in a day.

Thanks in advance,
Bob

-- 
Dr. Robert Williams
Department of Biomedical Informatics
Uniformed Services University
301-295-3568