[gmx-users] Re: parameter of RB potential for OPLS force field

[Mark Abraham]

Yanmei Song wrote:
> Dear Justin:
> 
> Thanks for your response. I saw this in the ffoplsaabon.itp, which I 
> think is a Periodic potential.

So check out table 5.4 in the manual and find out for sure!

>  [ dihedraltypes ]
> ;  i    j    k    l   func     coefficients
> ; Added DvdS for Quartz simulations
>    SI   OS    1     0.000       3.766      3
>    SI   OH    1     0.000       3.766      3
> 
> Does this mean that we can still use a periodic potential combined with 
> OPLS force field since it seems OPLS also consists of the periodic 
> potential besides RB. It doesn't have to be necessary to use RB for the 
> proper dihedral when you use OPLS force field, right?

What's necessary is to use parameters and functional forms that have 
been demonstrated to be parameterized for your observables. Mixing 
functional forms doesn't seem like something to encourage, but if it's 
been done already and you're happy with their results, then go for it.

Mark