[gmx-users] question about adding two functions for one torsional angle

[Ming-Tsung Lee]

Dear all,

I want to sum two functions for one torsional angle. Energy of the torsion
(say, 1 2 3 4) is the combination of Ryckaert-Bellemans (function no.3)
and compensated by periodic proper dihedral (function no.9). Is it
possible that I simply type the follows, and GROMACS will add it up?
          func.  parameters
1 2 3 4   3      ...
1 2 3 4   9      ...

I have search for the manual and articles, but I only found one possible
option to scan the text file for the torsion. However, I was wondering
whether there is a easy way to combined use two torsional functions for
one torsion? Thank you.

Best,
Lee