CCL: W:Calculation of displacements in vibrational normal modes with MOPAC

 Sent to CCL by: "Michael  Schmuker" [schmuker... |-at-|]
 Dear List,
 having only fundamental knowledge in quantum chemistry, I'm a bit lost on
 this one:
 I want to calculate vibrational normal modes of small organic molecules
 using MOPAC and the respective atom displacements for each of them. So far,
 I use MOPAC with the FORCE keyword, which gives me the frequencies of the
 vibrations and two matrices, the "Normal Coordinate Analysis" and the
 "Mass-Weighted Coordinate Analysis".
 Can anyone tell me how to get from there to the atom displacements (in
 x,y,z coordinates) for each vibrational mode? How can I calculate something
 like the example below from those matrices?
 Frequency 1234.5
 Atom1   0.002   0.012   -0.090
 Atom2  -0.123   0.087    0.089
 Frequency 3548.5
 Atom1   0.004   0.003    0.020
 Atom2   0.003  -0.014    0.089
 Many thanks in advance!
 Kind Regards,
 Michael Schmuker
 Beilstein Endowed Chair of Cheminformatics
 University of Frankfurt
 schmuker AT chemie uni-frankfurt de