[gmx-users] protein membrane simulation

[maite lopez]

Hi all:

Thanks a lot for replyng.  You 're right, i include the popc.itp file
in my .top and grompp runs well.  I've changed to ffG43a2 force field,
as David and Tsjerk said me, the ffG53a* isn't a good force field for
lipids. The best of the gromos96 ff is ffG43a4 for membrane
simulations,  but gromacs 3.3 hasn't it.

Chris, i found that  ffG43a2 requires the same valor of FudgeQQ than
the Berger lipids. I don't have to do this transformation. Thanks for
the last email. I could to mix the Berge and GROMOS96 force field
following your steps.

if somebody have to do something similar don't forget to change the
atoms OW1 x OW, HW2 x HW1 and HW3 x HW2  in the membrane.gro file.
Grompp gives these warnings:

Warning: atom names in membrane.top and membrane.gro don't match (OW - OW1)
Warning: atom names in membrane.top and membrane.gro don't match (HW1 - HW2)
.....

Cheers,

Maite