NVE ensemble - Revision history

Singraber at 08:01, 24 October 2025

2025-10-24T08:01:25Z

← Older revision		Revision as of 08:01, 24 October 2025
Line 11:		Line 11:
	\|style="text-align:center;"\| {{TAG\|MDALGO}} \|\| style="text-align:center;"\| 1 \|\| style="text-align:center;"\| 2		\|style="text-align:center;"\| {{TAG\|MDALGO}} \|\| style="text-align:center;"\| 1 \|\| style="text-align:center;"\| 2
	\|-		\|-
	\| additional tags to set \|\| style="text-align:center;"\| {{~~TAGO~~\|ANDERSEN_PROB\|0.0}} \|\|style="text-align:center;"\| {{~~TAGO~~\|SMASS\|-3}}		\| 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.		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.
	{{NB\|deprecated\|{{VASP}} comes with another, older implementation of the [[Nosé-Hoover thermostat]] which can be selected with {{~~TAGO~~\|MDALGO\|0\|color=grey}}. However, we recommend {{~~TAGO~~\|MDALGO\|2\|color=grey}} as stated above because the older variant comes with some drawbacks regarding post-processing: the atom coordinates in output files will always be wrapped back into the box if atoms cross the periodic boundaries. This makes it impossible to carry out certain analysis, e.g. computing the mean squared displacement (MSD).}} To enforce constant volume throughout the calculation, set {{~~TAGO~~\|ISIF\|3\|op=<}}. In NVE MD runs there is no control over temperature and pressure, their respective averages depend on the initial structure (lattice, atom positions provided in {{FILE\|POSCAR}}) and initial velocities (either set in {{FILE\|POSCAR}} or via {{TAG\|TEBEG}}). Hence, it is often desirable to equilibrate the system before sampling from the NVE ensemble. This can be achieved in various ways, for example, the system can be thermalized by performing an MD simulation in the [[NVT ensemble]] or thermalized and additionally its cell equilibrated via the [[NpT ensemble]]. Preparatory steps may also include non-MD algorithms, like structure and volume optimization with {{~~TAGO~~\|IBRION\|1 or 2}} and setting {{~~TAGO~~\|ISIF\|2\|op=>}}. A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.		{{NB\|deprecated\|{{VASP}} comes with another, older implementation of the [[Nosé-Hoover thermostat]] which can be selected with {{TAG\|MDALGO\|0\|color=grey}}. However, we recommend {{TAG\|MDALGO\|2\|color=grey}} as stated above because the older variant comes with some drawbacks regarding post-processing: the atom coordinates in output files will always be wrapped back into the box if atoms cross the periodic boundaries. This makes it impossible to carry out certain analysis, e.g. computing the mean squared displacement (MSD).}} To enforce constant volume throughout the calculation, set {{TAG\|ISIF\|3\|op=<}}. In NVE MD runs there is no control over temperature and pressure, their respective averages depend on the initial structure (lattice, atom positions provided in {{FILE\|POSCAR}}) and initial velocities (either set in {{FILE\|POSCAR}} or via {{TAG\|TEBEG}}). Hence, it is often desirable to equilibrate the system before sampling from the NVE ensemble. This can be achieved in various ways, for example, the system can be thermalized by performing an MD simulation in the [[NVT ensemble]] or thermalized and additionally its cell equilibrated via the [[NpT ensemble]]. Preparatory steps may also include non-MD algorithms, like structure and volume optimization with {{TAG\|IBRION\|1 or 2}} and setting {{TAG\|ISIF\|2\|op=>}}. A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.

	''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''		''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''

Singraber at 21:12, 17 October 2025

2025-10-17T21:12:31Z

← Older revision		Revision as of 21:12, 17 October 2025
Line 3:		Line 3:
	''' Instructions for setting up a NVE ensemble '''		''' Instructions for setting up a NVE ensemble '''

	There are multiple ways to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run which samples from the NVE ensemble in {{VASP}}. All options have in common that one of the available thermostats is selected but effectively disabled via their respective coupling parameters. The simplest and recommended way is to use the [[Andersen thermostat]] and setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero. Another possibility is to enable the [[~~Nose~~-Hoover thermostat]] and select the special value -3 for the mass of the virtual degree of freedom ({{TAG\|SMASS}}). Both presented options will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.		There are multiple ways to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run which samples from the NVE ensemble in {{VASP}}. All options have in common that one of the available thermostats is selected but effectively disabled via their respective coupling parameters. The simplest and recommended way is to use the [[Andersen thermostat]] and setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero. Another possibility is to enable the [[Nosé-Hoover thermostat]] and select the special value -3 for the mass of the virtual degree of freedom ({{TAG\|SMASS}}). Both presented options will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.
	See the following table for the corresponding {{TAG\|MDALGO}} setting and related tags.		See the following table for the corresponding {{TAG\|MDALGO}} setting and related tags.

	{\|class="wikitable" style="margin:aut		{\|class="wikitable" style="margin:aut
	! NVE ensemble !! Andersen !! ~~Nose~~-Hoover		! NVE ensemble !! Andersen !! Nosé-Hoover
	\|-		\|-
	\|style="text-align:center;"\| {{TAG\|MDALGO}} \|\| style="text-align:center;"\| 1 \|\| style="text-align:center;"\| 2		\|style="text-align:center;"\| {{TAG\|MDALGO}} \|\| style="text-align:center;"\| 1 \|\| style="text-align:center;"\| 2
Line 15:		Line 15:

	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.		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.
	{{NB\|deprecated\|{{VASP}} comes with another, older implementation of the [[~~Nose~~-Hoover thermostat]] which can be selected with {{TAGO\|MDALGO\|0\|color=grey}}. However, we recommend {{TAGO\|MDALGO\|2\|color=grey}} as stated above because the older variant comes with some drawbacks regarding post-processing: the atom coordinates in output files will always be wrapped back into the box if atoms cross the periodic boundaries. This makes it impossible to carry out certain analysis, e.g. computing the mean squared displacement (MSD).}} To enforce constant volume throughout the calculation, set {{TAGO\|ISIF\|3\|op=<}}. In NVE MD runs there is no control over temperature and pressure, their respective averages depend on the initial structure (lattice, atom positions provided in {{FILE\|POSCAR}}) and initial velocities (either set in {{FILE\|POSCAR}} or via {{TAG\|TEBEG}}). Hence, it is often desirable to equilibrate the system before sampling from the NVE ensemble. This can be achieved in various ways, for example, the system can be thermalized by performing an MD simulation in the [[NVT ensemble]] or thermalized and additionally its cell equilibrated via the [[NpT ensemble]]. Preparatory steps may also include non-MD algorithms, like structure and volume optimization with {{TAGO\|IBRION\|1 or 2}} and setting {{TAGO\|ISIF\|2\|op=>}}. A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.		{{NB\|deprecated\|{{VASP}} comes with another, older implementation of the [[Nosé-Hoover thermostat]] which can be selected with {{TAGO\|MDALGO\|0\|color=grey}}. However, we recommend {{TAGO\|MDALGO\|2\|color=grey}} as stated above because the older variant comes with some drawbacks regarding post-processing: the atom coordinates in output files will always be wrapped back into the box if atoms cross the periodic boundaries. This makes it impossible to carry out certain analysis, e.g. computing the mean squared displacement (MSD).}} To enforce constant volume throughout the calculation, set {{TAGO\|ISIF\|3\|op=<}}. In NVE MD runs there is no control over temperature and pressure, their respective averages depend on the initial structure (lattice, atom positions provided in {{FILE\|POSCAR}}) and initial velocities (either set in {{FILE\|POSCAR}} or via {{TAG\|TEBEG}}). Hence, it is often desirable to equilibrate the system before sampling from the NVE ensemble. This can be achieved in various ways, for example, the system can be thermalized by performing an MD simulation in the [[NVT ensemble]] or thermalized and additionally its cell equilibrated via the [[NpT ensemble]]. Preparatory steps may also include non-MD algorithms, like structure and volume optimization with {{TAGO\|IBRION\|1 or 2}} and setting {{TAGO\|ISIF\|2\|op=>}}. A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.

	''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''		''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''

Singraber at 09:45, 17 October 2025

2025-10-17T09:45:26Z

← Older revision		Revision as of 09:45, 17 October 2025
Line 3:		Line 3:
	''' Instructions for setting up a NVE ensemble '''		''' Instructions for setting up a NVE ensemble '''

	There are ~~two choices of thermostats which can be adjusted~~ to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run.		There are multiple ways to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run which samples from the NVE ensemble in {{VASP}}. All options have in common that one of the available thermostats is selected but effectively disabled via their respective coupling parameters. The simplest and recommended way is to use the [[Andersen thermostat]] and setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero. Another possibility is to enable the [[Nose-Hoover thermostat]] and select the special value -3 for the mass of the virtual degree of freedom ({{TAG\|SMASS}}). Both presented options will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.
	The [[Andersen thermostat]] ~~can be used by~~ setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero ~~and~~ the [[Nose-Hoover thermostat]] ~~by setting~~ the mass of the virtual degree of freedom ({{TAG\|SMASS}}) ~~to minus three~~. Both ~~settings~~ will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.		See the following table for the corresponding {{TAG\|MDALGO}} setting and related tags.
	See table for the corresponding {{TAG\|MDALGO}} setting and related tags.

	{\|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		\|style="text-align:center;"\| {{TAG\|MDALGO}} \|\| style="text-align:center;"\| 1 \|\| style="text-align:center;"\| 2
	\|-		\|-
	\| additional tags to set \|\| style="text-align:center;"\| {{~~TAG~~\|ANDERSEN_PROB~~}}=~~0.0 \|\|style="text-align:center;"\| {{~~TAG~~\|SMASS}}~~=-3~~		\| additional tags to set \|\| style="text-align:center;"\| {{TAGO\|ANDERSEN_PROB\|0.0}} \|\|style="text-align:center;"\| {{TAGO\|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.		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]]~~. To enforce constant volume throughout the calculation, {{~~TAG~~\|ISIF}} ~~has to be~~ set ~~to less than three~~. ~~The cell shape and volume have~~ to ~~be preoptimized when doing NVT simulations~~. This can ~~either~~ be ~~done with a~~ [[~~NpT_ensemble\|NPT~~]] [[~~Molecular dynamics calculations\|molecular-dynamics~~]] ~~run or by performing~~ structure and volume optimization with {{~~TAG~~\|IBRION~~}}=~~1 or 2 and setting {{~~TAG~~\|ISIF}}>2.		{{NB\|deprecated\|{{VASP}} comes with another, older implementation of the [[Nose-Hoover thermostat]] which can be selected with {{TAGO\|MDALGO\|0\|color=grey}}. However, we recommend {{TAGO\|MDALGO\|2\|color=grey}} as stated above because the older variant comes with some drawbacks regarding post-processing: the atom coordinates in output files will always be wrapped back into the box if atoms cross the periodic boundaries. This makes it impossible to carry out certain analysis, e.g. computing the mean squared displacement (MSD).}} To enforce constant volume throughout the calculation, set {{TAGO\|ISIF\|3\|op=<}}. In NVE MD runs there is no control over temperature and pressure, their respective averages depend on the initial structure (lattice, atom positions provided in {{FILE\|POSCAR}}) and initial velocities (either set in {{FILE\|POSCAR}} or via {{TAG\|TEBEG}}). Hence, it is often desirable to equilibrate the system before sampling from the NVE ensemble. This can be achieved in various ways, for example, the system can be thermalized by performing an MD simulation in the [[NVT ensemble]] or thermalized and additionally its cell equilibrated via the [[NpT ensemble]]. Preparatory steps may also include non-MD algorithms, like structure and volume optimization with {{TAGO\|IBRION\|1 or 2}} and setting {{TAGO\|ISIF\|2\|op=>}}. A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.
	A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.

	''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''		''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''

Singraber at 10:38, 21 November 2023

2023-11-21T10:38:59Z

← Older revision		Revision as of 10:38, 21 November 2023
Line 1:		Line 1:
	The [[NVE ensemble]] (micro-canonical ensemble) is a [[:Category:Ensembles\|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 <math>\langle E \rangle </math>~~. This page describes how to sample the NVE ensemble from a [[Molecular dynamics calculations\|molecular-dynamics]] run.		The [[NVE ensemble]] (micro-canonical ensemble) is a [[:Category:Ensembles\|statistical ensemble]] that is used to study material properties under the conditions of a constant particle number N, constant volume V and a conserved internal energy E (up to numerical inaccuracies). This page describes how to sample the NVE ensemble from a [[Molecular dynamics calculations\|molecular-dynamics]] run.

	''' Instructions for setting up a NVE ensemble '''		''' Instructions for setting up a NVE ensemble '''

Huebsch: Huebsch moved page Construction:NVE ensemble to NVE ensemble without leaving a redirect

2023-04-24T11:40:01Z

Huebsch moved page Construction:NVE ensemble to NVE ensemble without leaving a redirect

← Older revision	Revision as of 11:40, 24 April 2023
(No difference)

Jona at 15:12, 11 August 2022

2022-08-11T15:12:42Z

← Older revision		Revision as of 15:12, 11 August 2022
Line 1:		Line 1:
	The [[NVE ensemble]] (micro-canonical ensemble) is a [[:Category:Ensembles\|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]] (micro-canonical ensemble) is a [[:Category:Ensembles\|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 <math>\langle E \rangle </math>. This page describes how to sample the NVE ensemble from a [[Molecular dynamics calculations\|molecular-dynamics]] run.

	''' Instructions for setting up a NVE ensemble '''		''' Instructions for setting up a NVE ensemble '''

Jona at 14:35, 10 August 2022

2022-08-10T14:35:13Z

← Older revision		Revision as of 14:35, 10 August 2022
Line 30:		Line 30:
	{{TAGBL\|ANDERSEN_PROB}} = 0.0 # setting Andersen collision probability to zero to get NVE enseble		{{TAGBL\|ANDERSEN_PROB}} = 0.0 # setting Andersen collision probability to zero to get NVE enseble
	{{NB\|mind\| This {{FILE\|INCAR}} file only contains the parameters for the molecular-dynamics part. The [[Electronic minimization\|electronic minimization]] or the [[Machine-learned force fields\|machine learning]] tags have to be added.}}		{{NB\|mind\| This {{FILE\|INCAR}} file only contains the parameters for the molecular-dynamics part. The [[Electronic minimization\|electronic minimization]] or the [[Machine-learned force fields\|machine learning]] tags have to be added.}}


	==Related tags and articles==		==Related tags and articles==

Karsai at 11:21, 5 August 2022

2022-08-05T11:21:24Z

← Older revision		Revision as of 11:21, 5 August 2022
Line 5:		Line 5:
	There are two choices of thermostats which can be adjusted to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run.		There are two choices of thermostats which can be adjusted to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run.
	The [[Andersen thermostat]] can be used by setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero and the [[Nose-Hoover thermostat]] by setting the mass of the virtual degree of freedom ({{TAG\|SMASS}}) to minus three. Both settings will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.		The [[Andersen thermostat]] can be used by setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero and the [[Nose-Hoover thermostat]] by setting the mass of the virtual degree of freedom ({{TAG\|SMASS}}) to minus three. Both settings will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.
	See table for the corresponding MDALGO setting and related tags.		See table for the corresponding {{TAG\|MDALGO}} setting and related tags.

	{\|class="wikitable" style="margin:aut		{\|class="wikitable" style="margin:aut

Jona at 14:46, 20 July 2022

2022-07-20T14:46:47Z

← Older revision		Revision as of 14:46, 20 July 2022
Line 19:		Line 19:
	A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.		A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.

	''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]] ~~could look like~~''		''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]]''

	#INCAR molecular-dynamics tags NVE ensemble		#INCAR molecular-dynamics tags NVE ensemble

Jona at 14:46, 20 July 2022

2022-07-20T14:46:13Z

← Older revision		Revision as of 14:46, 20 July 2022
Line 16:		Line 16:

	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.		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]].		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]]. To enforce constant volume throughout the calculation, {{TAG\|ISIF}} has to be set to less than three. The cell shape and volume have to be preoptimized when doing NVT simulations. This can either be done with a [[NpT_ensemble\|NPT]] [[Molecular dynamics calculations\|molecular-dynamics]] run or by performing structure and volume optimization with {{TAG\|IBRION}}=1 or 2 and setting {{TAG\|ISIF}}>2.
	~~Other tags related to~~ molecular-dynamics simulations can be found [[Molecular dynamics calculations\|~~here~~]].		A general guide for molecular-dynamics simulations can be found on the [[Molecular dynamics calculations\|molecular-dynamics]] page.

	''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]] could look like''		''An example {{FILE\|INCAR}} file for the [[Andersen thermostat]] could look like''

← Older revision		Revision as of 11:21, 5 August 2022
Line 5:		Line 5:
	There are two choices of thermostats which can be adjusted to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run.		There are two choices of thermostats which can be adjusted to set up a [[Molecular dynamics calculations\|molecular-dynamics]] run.
	The [[Andersen thermostat]] can be used by setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero and the [[Nose-Hoover thermostat]] by setting the mass of the virtual degree of freedom ({{TAG\|SMASS}}) to minus three. Both settings will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.		The [[Andersen thermostat]] can be used by setting the collision probability ({{TAG\|ANDERSEN_PROB}}) with the fictitious heat bath to zero and the [[Nose-Hoover thermostat]] by setting the mass of the virtual degree of freedom ({{TAG\|SMASS}}) to minus three. Both settings will switch the thermostat off, such that the velocities are determined by the [[Hellmann-Feynman forces]] or [[Machine-learned force fields]] only.
	See table for the corresponding MDALGO setting and related tags.		See table for the corresponding {{TAG\|MDALGO}} setting and related tags.

	{\|class="wikitable" style="margin:aut		{\|class="wikitable" style="margin:aut