[gmx-users] Best Lipid parameters...

Erik Lindahl lindahl at stanford.edu
Fri Apr 26 18:36:57 CEST 2002

jozef hritz wrote:

>	Dear Senthil,
>I found Your question in gromacs mailing list. 
>Have you got answers? I can't find any in the mailing list and I am sure
>answer is interesting for many users.
>	Thanks
>								Jozef
>>I am working on a lipid/protein/water/ions system and am looking for the 
>>best forcefield available to describe this system.
>>I see that there is an improved lipid forcefield ffG43a2x in 
>>the  contributed topology section.
>>Is this the best lipid parameter file available? I understand that just
>>two new atomtypes have been added to the general gromos forcefield?
>>How different is this forcefield from Tielemens Lipid.itp available from 
>>his website? Any ideas or suggestions?
HI Jozef & Senthil,

I think I've covered this before, but it won't hurt to do it again: 
Gromos96 in general is a quite nice united atom force field, but the 
carbon parameters used to be optimized for shorter chains, so they gave 
way too low area/lipid for lipids.

The ffG43a2x is an extension where one of my diploma students 
reparametrized carbons to suit the CH3 and CH2 for long chains. These 
parameters reproduce the area/lipid of at least DPPC within 1% of the 
experimental value (it is slightly dependent on the size of your system 
too). We've used it for tons of simulations with very good results.

There are a newer set of Gromos96 carbon parameters which should improve 
the situation significantly, but I've not been able to test it myself 
and it's not included in the distribution yet.



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