[gmx-users] Explicitly defined nonbonded LJ pair terms?

[Michael Shirts]

So, I've been reading around, and am trying to figure out if it is
currently possible in Gromacs to explicitly define separate ij terms,
i.e., that override the combination rule for specific atom types.  In
other words, say I have an alkane in water -- I want to vary the C-O
interaction independent of the C-C and the O-O interaction.  Is there
a way to do this currently?

Thanks,
Michael