On Thu, Jun 04, 2009 at 03:46:59PM -0400, Justin A. Lemkul wrote: > > > Lucio Ricardo Montero Valenzuela wrote: >> The target forcefield will be G43a1. But I would move to more recent >> versions of GROMOS 53a5 or 53a6. > > A more empirical charge assignment is often a reasonable starting point for > assigning GROMOS charges. As I understand it, quantum calculations were > only done to get electron densities around each atom in various functional > groups; the subsequent parameterization was done empirically. You must > then verify that the parameters match some condensed-phase criteria (the > force field references will tell you what types). > > I have gotten reasonable results based on assigning charges from comparable > functional groups within the building blocks in, i.e. ffG53a6.rtp.
I can second that. charge transfer from comparable functional works adequately for the gromos force field. for opls/aa I've achieved satisfactory results with resp charges. I expect those will work well for amber too. compatibility between resp charges and the gromos force field is not straightforward. in any case, _any_ (new) parameterization needs to be verified and validated! cheers, marc -- Marc F. Lensink (Ph.D.) Structure and Function of Biological Membranes SFMB Centre for Structural Biology and Bioinformatics CSBB Université Libre de Bruxelles (ULB) marc.lens...@ulb.ac.be Boulevard du Triomphe - CP 263, B-1050 Brussels, Belgium tel: +32 2 650 5411 secr: +32 2 650 2013 fax: +32 2 650 5425 _______________________________________________ gmx-users mailing list gmx-users@gromacs.org http://www.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/mailing_lists/users.php