[gmx-users] LJ cut-off distance

[Bogdan Costescu]

2010/10/22 C. Batistakis <cbatiss at yahoo.gr>
>
> Dear Justin
>
> Actually, what I want to do is to kill the attraction part of the LJ substrate-polymer interaction. So, I was thinking to put the cut-off equal the 1,12σ (point with the lowest energy).
>
> Do you have any other idea how can I have only the repulsion part?

You could switch from using sigma+epsilon to using c6+c12 for LJ
interactions - see sections 5.3.3 and 5.7.1 in the manual; this would
give you individual control over the attractive and repulsive terms.
You don't mention if your forcefield parameters are all custom - if
apart from your LJ particles you use some atom types from a forcefield
with sigma+epsilon (like OPLSaa) you need to convert those to c6+c12
as well.

Cheers,
Bogdan