> Hi all, > > I am trying to do a membrane protein simulation. I want to use OPLS - AA > force field for protein and ffgmx (modified ffgmx force filed with lipid > parameters from user contribution section ) force field for POPE lipids. > > Is it is possible and advisable to use two different force fields for > protein and lipids?
In general, this way madness lies. Force fields are mathematical constructs that are optimized to approximately reproduce some experimental properties *in cooperation with itself*. There is no reason to expect that force field parameters for "bond strength" have any great correlation with an experimentally determined bond strength, and thus to have no correlation with a "bond strength" from another force field. Accordingly there's no reason to expect that a mixture of parts of different force fields will work well together. It's somewhat like taking half of a soccer team and half of a gridiron team and expecting them to be able to play rugby together. > Or else, Is there any all atom force field availble for lipid molecules > which I can use? CHARMM parameter sets optimized for combined protein & lipid calculations exist. Simplest would then be to use CHARMM or NAMD. If you want to use GROMACS, you can get such a force field, use my scripts available here http://www.gromacs.org/contributed_by_users/task,doc_details/gid,59/ to convert them to gromacs format, obtain some .rtp files elsewhere, test carefully, and simulate to your heart's content. Mark _______________________________________________ gmx-users mailing list gmx-users@gromacs.org 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
