Re: CCL:vibration spectras from force-field calculations

 	Dear Marc,
 >it would be kind if anyone could tell me if there exist a program that
 >calculates
 >vibrational spectras from forcefields like MM2 or DISCOVER or HYPERCHEM
 >.... for free ?
 >
 >do there any public domain routines exist, which are able to refine
 >existing forcefields
 >like mm2 or amber when the IR-spectrum is given ?
 	You should look up Tinker, from Jay Ponders lab.  Check it out at:
 http://dasher.wustl.edu/tinker
 	It's pretty hard to use IR spectra in the parameterization, and
 anyway, MM2 and AMBER aren't built to reproduce IR spectra.  A few
 molecular mechanics force fields are, for example MM3 (available in Tinker)
 and CFF.  In any case, I recommend parameterizing from a quantum chemical
 Hessian directly, not from the actual spectrum (a bit hard to do if what
 you have is the experimental spectrum :-).  In most cases, it's almost
 hopeless to match normal modes between calculated and experimental
 spectrum, whereas the Hessian elements are well defined.  Look up the work
 of Lifson & Warshel (CFF), Rasmussen (CFF-Lyngby), Hagler (CFF9x), Halgren
 (MMFF), ...
 	Best Regards,
 	Per-Ola Norrby
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  *  Per-Ola Norrby, Associate Professor
  *  The Royal Danish School of Pharmacy, Dept. of Med. Chem.
  *  Universitetsparken 2, DK 2100 Copenhagen, Denmark
  *  tel. +45-35376777-506, +45-35370850    fax +45-35372209
  *  Internet: peon &$at$& medchem.dfh.dk, http://compchem.dfh.dk/