COPSS (Continuum--Particle Simulation Software) augments
standard molecular dynamics and Monte-Carlo codes, permitting particle--field
coupling. COPSS presents not only a set of methods, but also aims to provide a
unified, extensible framework adaptable to generic molecular
simulations.
COPSS is open-source and distributed under the GNU General Public
License. It is developed at Argonne National Laboratory and the
University of Chicago.
Seamless Integration
COPSS is designed from the ground up to connect to arbitrary molecular
simulation codes through minimal programming effort. It targets
specific interoperability with open-source codes such as GROMACS and LAMMPS,
and is constantly growing to incorporate other open-source, proprietary,
and bespoke codes.
What does it do?
The continuum--particle coupling provided by COPSS enables the spanning of
multiple timescales in simulation. The initial suite of routines is built around
the General-geometry Ewald-like Method (GgEM) which enables simulations such as
that shown below, where a discrete polymer chain, representing DNA, is embedded
in a background solvent, and confined to a nanoscopic channel; without
coupling algorithms such as GgEM, such simulations are impossible.
The continuum--particle coupling of COPSS permits efficient simulation of
many-body systems such as the DNA nanoslit (see video) on the timescales of
polymer diffusion. In the first video, 84 kilobase DNA is simulated under
confinement in a nanochannel with full hydrodynamic coupling to itself and the
system boundaries.
COPSS also permits the simulation of electrostatic interactions with
polarization effects in heterogeneous dielectric media in an accurate, highly
efficient manner. In the second video, 10 polarizable micron-sized particles are
simulated in an vacuum environment where only long-range electrostatic
interaction and short-range excluded volume interaction affect their motion. The
electrostatic forces are calculated by COPSS at each time step, and the
particles' positions are evolved by coupling COPSS with LAMMPS.
