introduce better control over propagation in ESPResSo
avoid the currently somewhat arbitrary split of funcitonality between integrators and theremostats. In the end, users need to control the "equation of motion"
the first part of this was to allow a per-particle override of the system-wide default. This was merged end of 2023.
now, per-particle selection of propagation is quite different from system wide setup.
the goal is to have a consistent API for system-wide setup of propagation, i.e., the default that applies to all particles that do not explicitly override it.
Possible API
These are examples for a suggested API for system wide propagation setup, using the same Propagation objects that would be used to control propagation on the particle level.
from espressomd import Propagation
# Langevin for translation and rotation
system.propagation.set_params(
default=Propagation.TRANS_LANGVEVIN || Propagation.ROT_LANGEVIN,
kT=1,
gamma_trans = 1,
gamma_rot=2)
# LB coupling for translation and Langevin for rotation
system.propagation.set_params(
default=Propagation.TRANS_LB || Propagation.ROT_LANGEVIN,
kT=1,
gamma_trans = 1,
gamma_rot=2)
# ovverride for an individual particle
system.lb = LBFluidWalberla(...)
lb_tracer = system.part.add(pos=..., propagation=Propagation.LB_TRACER)
system.propagation.run(10)
One drawback is that it is necessary to import the Propagation class in all simulation scripts. On the other hand, then, the API for indidividual particles and the system-default are consistent.
Background
Possible API
These are examples for a suggested API for system wide propagation setup, using the same
Propagationobjects that would be used to control propagation on the particle level.One drawback is that it is necessary to import the Propagation class in all simulation scripts. On the other hand, then, the API for indidividual particles and the system-default are consistent.