[lammps-users] does lammps do free energy calculation

Dear lammps users,

Can lammps calculate free energy, using thermodynamic integration or umbrella sampling ?

Thanks for suggestions.

Xiandong Liu

Each of these methods requires several successive MD simulations.
LAMMPS can do the multiple simulations, but there is no automated
way to combine the results for TI or US. For US, there are fix spring
commands that can tether the molecule (or whatever) to a position
via a harmonic constraint.

Paul, do you want to comment additionally?


Xiandong Liu,

I agree with Steve's comment. Also, please review the docs for fix spring:


Note where umbrella sampling is mentioned. You might also consider
using "fix com" to keep track of the centers of mass of the groups you
are fixing.

I'd also refer you to Alan Grossfield's WHAM code:


that can be used to post-process LAMMPS results for computation of
free energies using WHAM.