Hi LAMMPS,
I’m trying to simulate a system under isothermal-isobaric conditions, and am using “fix npt” to use LAMMPS’ implementation of the NH barostat. To explore the effects of the damping parameter, I ran a number of otherwise identical simulations with a variety of values for “Pdamp.”
I find that even upon reaching apparent equilibrium, the distribution of sampled volumes is sensitive to this value. What is the standard way for calibrating this parameter so that the NPT ensemble is accurately sampled? Is there a standard method for validating the correctness of thermodynamics in the NPT and NVT ensembles?
I understand this is a science question, but imagine many users have experience with this.
Many thanks,
Anthony Frachioni
Binghamton University
Hi LAMMPS,
I'm trying to simulate a system under isothermal-isobaric conditions, and am
using "fix npt" to use LAMMPS' implementation of the NH barostat. To
explore the effects of the damping parameter, I ran a number of otherwise
identical simulations with a variety of values for "Pdamp."
I find that even upon reaching apparent equilibrium, the distribution of
sampled volumes is sensitive to this value. What is the standard way for
calibrating this parameter so that the NPT ensemble is accurately sampled?
Is there a standard method for validating the correctness of thermodynamics
in the NPT and NVT ensembles?
I understand this is a science question, but imagine many users have
experience with this.
two comments/questions:
- what kind of system? different setups and simulation
environments.(density, thermodynamic state, model, etc.) are
differently impacted by how well the NH mechanism works.
- how do/did you equilibrate your system? usually it is not the best
choice to start with fix npt right away, but either equilibrate with
fixed volume and/or high(er) pressure for a bit. if your system
expands too far, it can take a very, very long time until you really
(re)gain equilibrium state.
axel.