Maarten, What version of the code are you using? There was a bug in the angle restraints code until 3.3.1 (or 3.3 cvs) which caused angle restraints to turn off gradually as a function of lambda in free energy calculations, if I remember correctly. (See bugzilla for details: http://bugzilla.gromacs.org/show_bug.cgi?id=43).
However, I'm not sure that relates to the problem you're describing, but it probably does, depending on the version you are using. What exactly are you changing in the free energy calculation? Are you changing the angle restraint as a function of lambda? If so, which way are you changing it? Decreasing or increasing restraints? David On 5/11/06, Maarten Wolf <[EMAIL PROTECTED]> wrote:
Dear users, I have a small system with a number of small peptides. I want to constraint the angle between the N-term to C-term vectors of different peptides. This works well, but if I do a FEP calculation the dG/dl becomes smaller than zero at some point. I expected it to be at least allways greater than zero (zero in the limit that the restraint does not have to do anything), since a force has to be aplied to restraint the angles. Can anybody explain where I am going wrong? Thanks Maarten Send instant messages to your online friends http://uk.messenger.yahoo.com _______________________________________________ gmx-users mailing list [email protected] http://www.gromacs.org/mailman/listinfo/gmx-users Please don't post (un)subscribe requests to the list. Use the www interface or send it to [EMAIL PROTECTED] Can't post? Read http://www.gromacs.org/mailing_lists/users.php
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