AMBER Archive (2003)

Subject: AMBER/FEP: RESP charges

From: Ghislain Deslongchamps (ghislain_at_unb.ca)
Date: Fri Mar 14 2003 - 07:37:13 CST

Hi folks,

Using AMBER 7/GIBBS, we are mutating a phenol group (Ar-O-H) into a benzene
(Ar-H-Du, Du=dummy) in a 54-carbon molecule using electrostatic decoupling.
RESP charges were calculated for both molecules. Since the RESP charges are
different for all atoms on both structures, is GIBBS flagging all the atoms
as part of the intra-perturbed group? Our FEP results gave erroneous
electrostatic energy terms unless intra-perturbed group interactions were
omitted (INTPRT=0).

Should this resolve itself if we use the same RESP charges on all atoms on
both molecules except those directly involved in the mutation?

Any help will be gratefully appreciated,

-Ghislain

-----------------------------------------------------------
 Dr. Ghislain Deslongchamps, Professor
 Director of Undergraduate Studies
 Department of Chemistry, Faculty of Science
 University of New Brunswick
 Fredericton, N.B. CANADA E3B 6E2
 phone: (506) 453-4795 cell: 451-5166 FAX: 453-4981
 e-mail: ghislain_at_unb.ca WWW: http://biocomp.chem.unb.ca
-----------------------------------------------------------