Subject: How to get QM contribution to Free Energy

From: Shijie Yao <[email-masked]>
Date: Mon, 26 Jun 1995 12:13:53 -0400

Dear Netters

   We are using free energy perturbation calculation
to get the solvation free energy difference for this
reaction.

             H              R
             |              |
           /\/\/\         /\/\/\
          |O|O|O| -----> |O|O|O|
           \/\/\/         \/\/\/

          anthracene    9-R anthracene
                        R could be anything
                        (e.g. CH3, CH2CH3 etc.)

   Could some one please tell us how to treat the
quantum mechanical energy contribution in the reaction
of anthracene ---> 9-R anthracene (R could be anything
e.g. CH3, CH2CH3 etc.)?

   According to Prof. Kollman's papers, we need to add
the quantum mechanical energy contribution of changing
anthracene to substituted anthracene and the
zero point vibrational energy difference between the
two systems to the solvation free energy to get the
total free energy change for the reaction (We also
would like to know an explanation why we need to add
the quantum mechanical energy contribution and zero
point vibrational energy difference).

   Please write directly to me  at

            [email-masked]
I'll summarize the responses if there is enough interest.

Thanks for your help.

chessyx