[gmx-users] charmm c36 lipids

[Thomas Piggot]

Hi Par,

I have a working version of the CHARMM36 lipids that I converted myself, 
which I am fairly confident is correct. I shall check your parameters 
against my ones to confirm everything is the same and report back to the 
list. I don't see anything which would not work for your script as there 
are not any major changes to the forcefield in CHARMM36.

Cheers

Tom

Pär Bjelkmar wrote:
> Hello Sven, Drew and gmx-users,
> 
> I've gotten requests from users that want to use the c36 CHARMM lipids 
> in GROMACS (see below). So I answer both of you and the rest of the 
> community in this e-mail. 
> 
> I have a script that parses the top and par files of CHARMM force 
> field(s). It's not the most general piece of code there is so it will 
> not be able to convert files that do not follow the format the CHARMM 
> top and par files had when I wrote it (version c32b1). Also, it cannot 
> parse the toppar files (i.e. what's called the toppar stream files in 
> CHARMM). I downloaded the force field from:
> http://mackerell.umaryland.edu/download.php?filename=CHARMM_ff_params_files/toppar_lipid_all36.tgz
> 
> My script is able to parse the top_lipid_all36.rtf and 
> par_all36_lipid.prm files without any errors and generate the 
> corresponding GROMACS rtp, atp, bonded and nonbonded files. I'm not an 
> CHARMM expert but if they haven't changed the force field considerable 
> lately (by changing parameter definitions and functional forms of the 
> force field for example) the files generated by the script should be the 
> correct GROMACS translation. However, I cannot guarantee that all went 
> well so I would suggest that those of you who are interested in this 
> look through the files and convince yourself that the script did the job 
> before running production runs with these parameters. 
> 
> I've put it on the old (and outdated) port homepage 
> (http://www.dbb.su.se/User:Bjelkmar/Ffcharmm) so that those of you who 
> are interested in this can access and test it. If nothing seems to be 
> wrong after some of you have tested it I'm going to add it to the user 
> contributions on gromacs.org <http://gromacs.org>.
> 
> Regards,
> Pär Bjelkmar
> 
> 1 okt 2010 kl. 09.53 skrev Sven Jakobtorweihen:
> 
>> Dear Pär Bjelkmar,
>>
>> thanks for implementing the CHARMM force field into GROMACS, that is 
>> really useful. Recently the CHARMM developers have introduced an 
>> updated lipid force field CHARMM36 for lipids, see Klauda et al. J. 
>> Phys. Chem. B, 2010, 114, 7830 (doi: 10.1021/jp101759q). It seems that 
>> this is an important improvement over the preceding version. I checked 
>> gromacs version 4.5.1 and the git-repository; unfortunately, the 
>> charmm36 lipids are not yet available in gromacs. However, I could 
>> write some scripts to convert the charmm files to gromacs files, I 
>> have the feeling the bonded parameter conversion is straight forward 
>> (having the charmm27 files for gromacs), but I fear that transferring 
>> the bonded parameters is tedious. So my question is: Do you have by 
>> any change already gromacs files for charmm36 lipids? Or are scripts 
>> available to convert charmm FF to gromacs FF files? I am aware of the 
>> charmm_to_gromacs perl scripts on the gromacs website. But as fare as 
>> I know they are not compatible with the official implementation of 
>> charmm in gromacs, or am I wrong?
>>
>> Thanks for your help.
>>
>> Best regards,
>> Sven
>>
>> -- 
>> *****************************************
>> Dr.-Ing. Sven Jakobtorweihen
>>
>> Hamburg University of Technology
>> Institute of Chemical Reaction Engineering / V2
>> Eissendorfer Str. 38
>> 21073 Hamburg
>> Germany
>>
>> PHONE : ++49 (0) 40 42878 2491
>> FAX   : ++49 (0) 40 42878 2145
>> E-MAIL: jakobtorweihen at tuhh.de <mailto:jakobtorweihen at tuhh.de>
>> *****************************************
>>
> 
> 
> 
>> 3 sep 2010 kl. 20.56 skrev Drew Bennett:
>>
>>> Dear Pr Bjelkmar,
>>>
>>> I saw on the gromacs mailing list that you have python a script for 
>>> converting CHARMM ff to GMX.
>>> I would greatly appreciate if you could please send it to me.
>>> I am trying to use the new CHARMM36 lipids for a simulation with a 
>>> membrane protein.
>>>
>>> Thank-you.
>>> Drew Bennett
>>

-- 
Dr Thomas Piggot
University of Southampton, UK.