NVT ensemble: Difference between revisions
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This page describes how to sample the NVT ensemble from a [[Molecular dynamics calculations|molecular dynamics]] run. | This page describes how to sample the NVT ensemble from a [[Molecular dynamics calculations|molecular dynamics]] run. | ||
''' Instructions for setting up a NVT ensemble ''' | |||
There are 4 choices of thermostats which can either be stochastic or deterministic to simulate the NVT ensemble. | There are 4 choices of thermostats which can either be stochastic or deterministic to simulate the NVT ensemble. | ||
The stochastic [[Andersen thermostat]] or [[Langevin thermostat]], | The stochastic [[Andersen thermostat]] or [[Langevin thermostat]], | ||
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The user is not allowed to set ISF>2 because then the volume of the simulation would be allowed to change | The user is not allowed to set ISF>2 because then the volume of the simulation would be allowed to change | ||
and the simulation would not result in a NVT ensemble. Setting ISIF=0 will speed up the calculation because the stress | and the simulation would not result in a NVT ensemble. Setting ISIF=0 will speed up the calculation because the stress | ||
tensor is not computed. | tensor is not computed. The tag {{TAG|IBRION}} has to be set to zero. | ||
Revision as of 13:01, 19 July 2022
Category: NVT ensemble == NVT ensemble == The NVT ensemble is a statistical ensemble that is used to study material properties under the conditions of a constant particle number N, constant volume V and a temperature fluctuating around an equilibrium value T. This page describes how to sample the NVT ensemble from a molecular dynamics run. Instructions for setting up a NVT ensemble There are 4 choices of thermostats which can either be stochastic or deterministic to simulate the NVT ensemble. The stochastic Andersen thermostat or Langevin thermostat, the deterministic Nose-Hoover thermostat or Multiple Anderson thermostats can be used. See table for the corresponding MDALGO tags.
| NVT ensemble | Andersen | Langevin | Nose-Hoover | Multiple Andersen |
|---|---|---|---|---|
| MDALGO | 1 | 3 | 2 | 13 |
| additional tags | ANDERSEN_PROB | LANGEVIN_GAMMA | SMASS | NSUBSYS, TSUBSYS, PSUBSYS |
The user is not allowed to set ISF>2 because then the volume of the simulation would be allowed to change and the simulation would not result in a NVT ensemble. Setting ISIF=0 will speed up the calculation because the stress tensor is not computed. The tag IBRION has to be set to zero.