This implementation of the constant potential method is deprecated. You can find the new version here:
https://github.com/robeme/lammps/tree/electrode
This version of the LAMMPS software package features an implementation of the constant potential method (CPM).
The fix charge_update implements the CPM. Charges of groups specified as group-ID and with the couple keyword are adapted to meet their respective potential at every time step. An arbitrary number of electrodes can be set but the respective groups may not overlap. Electrode charges are smeared with a Gaussian charge distribution with reciprocal width eta. The energy minimization is achieved via matrix inversion.
fix [ID] [group-ID] charge_update [ψ] [η] [optional keyword] [optional value] ...
ID = ID of FIX command
group-ID = Group for 'first' electrode
η = Gaussian width parameter in angstrom-1
ψ = charges such that group-ID has a potential ψ volts.
couple [group-ID2] [ψ] = second electrode coupled to the first that has a
potential of ψ volts.
write_inv [file name] = store inverse of electrode-electrode matrix in a file
for later reuse.
read_inv [file name] = read inverse of electrode-electrode matrix.
symm [on/off] = use symmetric matrix as defined in Scalfi et al. (PCCP, 2020, 22, 10480) to ensure
charge neutrality.
The fix necessitates the use of a long range solver that can provide the matrix of electrode-electrode interactions and a vector of electrode-electrolyte interactions. The Kspace styles ewald/conp and pppm/conp are created specifically for this task.
For systems with non-periodic boundaries in one or two directions dipole corrections are available with the kspace_modify. For ewald/conp a two-dimensional Ewald summation can be used by setting “slab ew2d”:
Specific examples on how to use this code be found in the directory "./examples/USER/conp/".
In order to install the package with cmake use "cmake -D PKG_USER-CONP=yes ." and make sure the KSPACE package is installed. A traditional make with "make-yes user-conp" requires that the linalg library is previously build. The linalg library is found in lib/linalg. See the readme therein for more details on how to compile it.
More information on this specific implementation can be found under:
https://doi.org/10.1063/5.0063381
This is the LAMMPS software package.
LAMMPS stands for Large-scale Atomic/Molecular Massively Parallel Simulator.
Copyright (2003) Sandia Corporation. Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains certain rights in this software. This software is distributed under the GNU General Public License.
LAMMPS is a classical molecular dynamics simulation code designed to run efficiently on parallel computers. It was developed at Sandia National Laboratories, a US Department of Energy facility, with funding from the DOE. It is an open-source code, distributed freely under the terms of the GNU Public License (GPL).
The primary author of the code is Steve Plimpton, who can be emailed at sjplimp@sandia.gov. The LAMMPS WWW Site at lammps.sandia.gov has more information about the code and its uses.
The LAMMPS distribution includes the following files and directories:
- README this file
- LICENSE the GNU General Public License (GPL)
- bench benchmark problems
- cmake CMake build files
- doc documentation
- examples simple test problems
- fortran Fortran wrapper for LAMMPS
- lib additional provided or external libraries
- potentials interatomic potential files
- python Python wrappers for LAMMPS
- src source files
- tools pre- and post-processing tools
Point your browser at any of these files to get started:
https://lammps.sandia.gov/doc/Manual.html LAMMPS manual
https://lammps.sandia.gov/doc/Intro.html hi-level introduction
https://lammps.sandia.gov/doc/Build.html how to build LAMMPS
https://lammps.sandia.gov/doc/Run_head.html how to run LAMMPS
https://lammps.sandia.gov/doc/Commands_all.html Table of available commands
https://lammps.sandia.gov/doc/Library.html LAMMPS library interfaces
https://lammps.sandia.gov/doc/Modify.html how to modify and extend LAMMPS
https://lammps.sandia.gov/doc/Developer.html LAMMPS developer info\
You can also create these doc pages locally:
% cd doc
% make html # creates HTML pages in doc/html
% make pdf # creates Manual.pdf