[lammps-users] Any EhN and HtN Ensembles in LAMMPS?

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1

Hello Lammps Users and Developers,
  
I would like to inquire if it's possible to perform EhN and HtN ensemble simulations in LAMMPS. I am planning to compute adiabatic elastic constants calculation using these ensembles in LAMMPS.

If not, I am wondering if anyone on the list has modify/perform simulations in these ensemble using lammps.

Suleiman.

2

I don't know of any. But they would simply be a "fix" in
LAMMPS, like the current fix nvt or fix npt or fix nph.
So you (or someone) could write a fix ehn.

Steve

3

Hello Once again,

I am thinking of using NVE in a way that the box parameters h = (a, b, c) can be rescaled every time step to get an EhN ensemble. I am not sure if there is any combination of fixes that can do that. I know that the h vector is normally define for NPT, but I'm not sure if it works with NVE.

For HtN, I should be fine using NPH, with pressure set to zero. This will essentially be HtN with thermodynamic tension t = 0. However for t not equal to zero, one will need to implement the extended Hamiltonian to compute thermodynamic tension tensors. For now, I need to use t = 0 but I am not not sure if LAMMPS implementation of NPH ensemble will lead to the desired outcome.

Any suggestion NVE to EhN using the h = (a,b,c) matrix?

Suleiman.

I don't know of any. But they would simply be a "fix" in
LAMMPS, like the current fix nvt or fix npt or fix nph.
So you (or someone) could write a fix ehn.

Steve

4

Again, if you write your own fix ehn or htn, you have control
over all the box params, so you can do whatever you want.

Steve