I am simulating a system consisting of 128 phosphonium ions made of one central charged phosphorous atom with four alkyle ligand and 128 negative borate ions. When I simulate this system at constant pressure using run_style respa with the recommended parameters in the manual
I get the correct density or at least a density that agrees with the one obtained from other programs but only if the timestep is very short - 0.4 fs. Therefore I wonder whether there is a better choice of paramters for run_style respa. I use the following paramteres:
you already posted this question. if you don't like the answer you
get, don't just repost the same question, but provide a reason why you
consider the answer you got is not satisfactory.
I am simulating a system consisting of 128 phosphonium ions made of one
central charged phosphorous atom with four alkyle ligand and 128 negative
borate ions. When I simulate this system at constant pressure using
run_style respa with the recommended parameters in the manual
but why should that work on your system, when you have already
confirmed that you cannot run at a typical time step for such systems
with verlet run style.
the system contracts to an unphysically high density. If I use this
alternative:
I get the correct density or at least a density that agrees with the one
obtained from other programs but only if the timestep is very short - 0.4
fs. Therefore I wonder whether there is a better choice of paramters for
run_style respa. I use the following paramteres:
i already told you, that the problem is likely not with respa, but
your parameters.
you probably just have a metastable state in one case and not in the
other. that doesn't make it correct.
in general, you *first* have to properly get the verlet run style to
work before even considering using respa. also, on modern hardware, i
don't see much of a benefit using the inner/middle/outer scheme ...and
finally a 10.0 angstrom cutoff is very short for the current state of
the art.