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Re: [lammps-users] On adding a density and temperature dependent Yukawa force in LAMMPS
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Re: [lammps-users] On adding a density and temperature dependent Yukawa force in LAMMPS


From: Steve Plimpton <sjplimp@...24...>
Date: Wed, 13 Dec 2017 07:26:06 -0700

The components of the force field you describe sound different enough
I don't think they would all match what fix ttm is doing.

1) sounds like a pair style
2) sounds like it could use parts of a KSpace style like
     PPPM which also solves a Poisson eq
3) also sounds like an EAM-style calculation using
    neighboring atoms to infer a density at each atom,
    see pair eam
4) this is like fix ttm

Steve



On Mon, Dec 11, 2017 at 2:53 PM, Abdourahmane Diaw <rahmane@...7283.....> wrote:
Dear LAMMPS developers,

I am trying to implement an electron model into LAMMPS.

This model is already in the ddcMD code of LLNL but this code is not open-source. My goal is to build this into LAMMPS.

The main features of this model called MOD-MD (as Multiscale Orbitial Free density functional theory- Molecular Dynamics) are as follows:
  1. Ions interact through a generalized Yukawa force F[ne,Te,Z*]. Here ne(r) is the electrons density, T_e(t) is their temperature and Z* is the average ionization.
  2. Electrons density is obtained from OFDFT, by basically solving a Poisson equation.
  3. Ionization state Z* is calculated with an average atom model.
  4. Electron temperature is obtained according to the heat diffusion equation. A technique similar to what the TTM fix does.
I am trying to build all these into the fix_ttm.cpp. However, I am not sure if this is the right way to do this in LAMMPS.

I would very much appreciate any suggestions and recommendations on how this could be done successfully in LAMMPS.

Best wishes,
Rahm

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