[gmx-users] External sinusoidal force

[Alex]

Hi all,

I asked this before and I think I remember the answer, so this is just to
make sure, before we move to another software package.

1. We need a sinusoidal force of given direction, amplitude, and frequency
applied to a selected group of atoms. Mimicking it with giving those atoms
charge and applying an electric field is not an option. Is there absolutely
anything else we can attempt?

2. Is this something I could request as a feature that could be implemented
quickly (within weeks)? Same type of mdp syntax, except also input for the
group. If it takes a while, makes no sense for us to wait, because LAMMPS
can do it. The issue with LAMMPS is that it is ~5 times slower than Gromacs
when using similar forcefields.

Thank you,

Alex