NVE ensemble: Difference between revisions
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The NVE 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 an internal energy E fluctuating around an equilibrium value E. This page describes how to sample the NVE ensemble from a [[Molecular dynamics calculations|molecular dynamics]] run. | The NVE 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 an internal energy E fluctuating around an equilibrium value E. This page describes how to sample the NVE ensemble from a [[Molecular dynamics calculations|molecular dynamics]] run. | ||
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For the NVE ensemble there are two equivalent choices of tags to set up a [[Molecular dynamics calculations|molecular dynamics]] run. | For the NVE ensemble there are two equivalent choices of tags to set up a [[Molecular dynamics calculations|molecular dynamics]] run. | ||
The user can either | The user can either set the [[Andersen thermostat]] or the [[Nose-Hoover thermostat]] to give a NVE ensemble. The [[Andersen thermostat]] thermostat can be used by setting the collision probability ({{TAG|ANDERSEN_PROB}}) with the fictitious heat bath to zero and [[Nose-Hoover thermostat]] by setting the mass of the virtual degree to minus three. | ||
can be used by setting the collision probability with the fictitious heat | |||
{|class="wikitable" style="margin:aut | {|class="wikitable" style="margin:aut | ||
! NVE ensemble !! Andersen !! Nose-Hoover | ! NVE ensemble !! Andersen !! Nose-Hoover | ||
|- | |||
|style="text-align:center;"| {{TAG|MDALGO}} || style="text-align:center;"| 1 || style="text-align:center;"| 0 or 2 | |||
|- | |- | ||
| | | additional tags to set || style="text-align:center;"| {{TAG|ANDERSEN_PROB}}=0.0 ||style="text-align:center;"| {{TAG|SMASS}}=-3 | ||
|- | |||
|} | |} | ||
The additional tags in the column for every thermostat have to be set to the given values. Otherwise the NVE ensemble will not be realized. | |||
There are two implementations of the [[Nose-Hoover thermostat]] in VASP which will give the same results. The {{TAG|MDALGO}}=0 version can be used even if the code was compiled without the precompiler option [[Precompiler_options#-Dtbdyn|-Dtbdyn]]. | |||
Revision as of 10:57, 20 July 2022
The NVE 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 an internal energy E fluctuating around an equilibrium value E. This page describes how to sample the NVE ensemble from a molecular dynamics run.
Instructions for setting up a NVE ensemble
For the NVE ensemble there are two equivalent choices of tags to set up a molecular dynamics run. The user can either set the Andersen thermostat or the Nose-Hoover thermostat to give a NVE ensemble. The Andersen thermostat thermostat can be used by setting the collision probability (ANDERSEN_PROB) with the fictitious heat bath to zero and Nose-Hoover thermostat by setting the mass of the virtual degree to minus three.
| NVE ensemble | Andersen | Nose-Hoover |
|---|---|---|
| MDALGO | 1 | 0 or 2 |
| additional tags to set | ANDERSEN_PROB=0.0 | SMASS=-3 |
The additional tags in the column for every thermostat have to be set to the given values. Otherwise the NVE ensemble will not be realized. There are two implementations of the Nose-Hoover thermostat in VASP which will give the same results. The MDALGO=0 version can be used even if the code was compiled without the precompiler option -Dtbdyn.