[gmx-users] How could I know whether I should use epsilon-sigma or c6-c12?

[Mark Abraham]

On 5/06/2012 4:34 PM, Bao Kai wrote:
> Hi, all,
>
> I am still trying to do my simulation with liquid mixtures.
>
> I have a simple question now. When I writing my .top file, how could I
> know if I should use epsilon-sigma or c6-c12 parameters for the LJ
> potential? It seems that in some examples, c6-c12 parameters are used
> and epsilon-sigma parameters are used in some other examples.

The model you are implementing chooses this and the rule by which 
parameters of different atom types get combined into interaction type 
parameters. The rationale for that choice often seems vague, IMO 
probably doesn't matter much, and is not really your problem until you 
go to design models. Literature is your friend, here.

Mark