[gmx-users] New force fields

[David van der Spoel]

On Fri, 3 May 2002, Ram'on Garc'ia Fern'andez wrote:

>> For generating starting conformations I would think LJ with softcore would 
>> be quite pain-free. 
>
>But at present, it is almost imposible to do LJ with softcore.
It's two parameters in the mdp file. Set sc_alpha to e.g. 1.5
; Free energy control stuff =
sc-alpha                 = 0
sc-sigma                 = 0.3

then you blow up the box by a factor of say 1.5, minimize, and do softcore 
MD with pressure coupling.

>Gromacs should document how to add a custom potential by formula to
>the source code, and allow with a reasonable amount of paramenters (such as
>four). It was straightforward with DLPOLY, I just modified forgen.f.

I agree we could have more documentation, but that costs time as well...

Groeten, David.
________________________________________________________________________
Dr. David van der Spoel, 	Biomedical center, Dept. of Biochemistry
Husargatan 3, Box 576,  	75123 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://zorn.bmc.uu.se/~spoel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++