IBRION - Revision history

Singraber at 07:44, 24 October 2025

2025-10-24T07:44:49Z

Schlipf at 10:07, 17 February 2025

2025-02-17T10:07:55Z

← Older revision		Revision as of 10:07, 17 February 2025
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	:::** {{TAG\|IBRION}}=44 [[improved dimer method]]		:::** {{TAG\|IBRION}}=44 [[improved dimer method]]

	:::* [[#~~User-~~supplied ~~interactive changes~~\|User-supplied interactive changes]]		:::* [[#Interactively supplied positions and lattice vectors\|User-supplied interactive changes]]
	:::** {{TAG\|IBRION}}=11 from standard input		:::** {{TAG\|IBRION}}=11 from standard input
	:::** {{TAG\|IBRION}}=12 from Python plugin		:::** {{TAG\|IBRION}}=12 from Python plugin

Huebsch: /* Interactively supplied positions and lattice vectors */

2025-01-07T11:06:55Z

Interactively supplied positions and lattice vectors

← Older revision		Revision as of 11:06, 7 January 2025
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	* With {{TAGO\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}>=3, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.		* With {{TAGO\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}>=3, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.

	* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[~~Writing a Python plugin~~\|write a Python plugin]] to modify the structure. Set {{TAGO\|IBRION\|12}} or {{TAGO\|PLUGINS/STRUCTURE\|T}} to activate it.		* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Plugins\|write a Python plugin]] to modify the structure. Set {{TAGO\|IBRION\|12}} or {{TAGO\|PLUGINS/STRUCTURE\|T}} to activate it.

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

Huebsch at 11:06, 7 January 2025

2025-01-07T11:06:33Z

← Older revision		Revision as of 11:06, 7 January 2025
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	* With {{TAGO\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}>=3, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.		* With {{TAGO\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}>=3, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.

	~~<!--~~
	* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Writing a Python plugin\|write a Python plugin]] to modify the structure. Set {{TAGO\|IBRION\|12}} or {{TAGO\|PLUGINS/STRUCTURE\|T}} to activate it.		* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Writing a Python plugin\|write a Python plugin]] to modify the structure. Set {{TAGO\|IBRION\|12}} or {{TAGO\|PLUGINS/STRUCTURE\|T}} to activate it.
	~~-->~~

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

Huebsch: /* Related tags and articles */

2025-01-07T11:05:51Z

Huebsch: /* Computing the phonon modes */

2024-10-18T12:53:07Z

Computing the phonon modes

← Older revision		Revision as of 12:53, 18 October 2024
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	== Computing the phonon modes ==		== Computing the phonon modes ==

	The second-order derivatives of the total energy <math>E</math> with respect to ionic positions <math>R_{\alpha i}</math> of ion <math>\alpha</math> in the direction of <math>i</math>, is computed using a first-order derivative of the [[forces]] <math>F_{\beta j}</math>. Then, the dynamical matrix <math>D_{\alpha i \beta j}</math> is constructed, diagonalized, and the phonon modes and frequencies of the system are reported in the {{FILE\|OUTCAR}} file and {{FILE\|vaspout.h5}}. Also see [[Phonons: Theory\|theory on phonons]].		The second-order derivatives of the total energy <math>E</math> with respect to ionic positions <math>R_{\alpha i}</math> of ion <math>\alpha</math> in the direction <math>i</math>, is computed using a first-order derivative of the [[forces]] <math>F_{\beta j}</math>. Then, the dynamical matrix <math>D_{\alpha i \beta j}</math> is constructed, diagonalized, and the phonon modes and frequencies of the system are reported in the {{FILE\|OUTCAR}} file and {{FILE\|vaspout.h5}}. Also see [[Phonons: Theory\|theory on phonons]].
	{{NB\|tip\|It ~~is often~~ necessary to set {{TAGO\|EDIFF\|<= 1E-6}} because the default ({{TAGO\|EDIFF\|1E-4}}) often results in unacceptably large errors.}}		{{NB\|tip\|It may be necessary to set {{TAGO\|EDIFF\|<= 1E-6}} because the default ({{TAGO\|EDIFF\|1E-4}}) often results in unacceptably large errors.}}
	VASP implements two different methods to compute the phonon modes and can use symmetry to reduce the number of computed displacements:		VASP implements two different methods to compute the phonon modes and can use symmetry to reduce the number of computed displacements:

Schlipf: /* User-supplied interactive changes to positions and lattice vectors */

2024-10-18T11:07:29Z

User-supplied interactive changes to positions and lattice vectors

← Older revision		Revision as of 11:07, 18 October 2024
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	* The [[nudged elastic bands]] method finds an approximate reaction path based on the initial and final structure, i.e., reactant and product.		* The [[nudged elastic bands]] method finds an approximate reaction path based on the initial and final structure, i.e., reactant and product.

	== ~~User-~~supplied ~~interactive changes to~~ positions and lattice vectors ==		== Interactively supplied positions and lattice vectors ==

	Occasionally, you may want to run VASP for related structures where the overhead of restarting VASP is significant.		Occasionally, you may want to run VASP for related structures where the overhead of restarting VASP is significant.

Schlipf: /* User-supplied interactive changes to positions and lattice vectors */

2024-10-18T11:05:02Z

User-supplied interactive changes to positions and lattice vectors

← Older revision		Revision as of 11:05, 18 October 2024
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	* With {{TAGO\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}>=3, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.		* With {{TAGO\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}>=3, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.

			<!--
	* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Writing a Python plugin\|write a Python plugin]] to modify the structure. Set {{TAGO\|IBRION\|12}} or {{TAGO\|PLUGINS/STRUCTURE\|T}} to activate it.		* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Writing a Python plugin\|write a Python plugin]] to modify the structure. Set {{TAGO\|IBRION\|12}} or {{TAGO\|PLUGINS/STRUCTURE\|T}} to activate it.
			-->

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

Schlipf: Split how-to part of IBRION into new page "structure optimization"

2024-10-18T11:04:29Z

Split how-to part of IBRION into new page "structure optimization"

Show changes

Csheldon: /* IBRION=1: ionic relaxation (RMM-DIIS). */

2024-07-10T08:29:07Z

IBRION=1: ionic relaxation (RMM-DIIS).

← Older revision		Revision as of 08:29, 10 July 2024
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	#If {{TAG\|NFREE}} is not specified, the criterion whether information is removed from the iteration history is based on the eigenvalue spectrum of the inverse Hessian matrix: if one eigenvalue of the inverse Hessian matrix is larger than 8, information from previous steps is discarded.		#If {{TAG\|NFREE}} is not specified, the criterion whether information is removed from the iteration history is based on the eigenvalue spectrum of the inverse Hessian matrix: if one eigenvalue of the inverse Hessian matrix is larger than 8, information from previous steps is discarded.

	For complex problems {{TAG\|NFREE}} can usually be set to a rather large value (i.e. 10-20), however systems of low dimensionality require a ~~carful~~ setting of {{TAG\|NFREE}} (or preferably an exact counting of the number of degrees of freedom). To increase {{TAG\|NFREE}} beyond 20 rarely improves convergence. If {{TAG\|NFREE}} is set to too large, the RMM-DIIS algorithm might diverge.		For complex problems {{TAG\|NFREE}} can usually be set to a rather large value (i.e. 10-20), however systems of low dimensionality require a careful setting of {{TAG\|NFREE}} (or preferably an exact counting of the number of degrees of freedom). To increase {{TAG\|NFREE}} beyond 20 rarely improves convergence. If {{TAG\|NFREE}} is set to too large, the RMM-DIIS algorithm might diverge.

	The choice of a reasonable {{TAG\|POTIM}} is also important and can speed up calculations significantly, we recommend to find an optimal {{TAG\|POTIM}} using {{TAG\|IBRION}}=2 or performing a few test calculations (see below).		The choice of a reasonable {{TAG\|POTIM}} is also important and can speed up calculations significantly, we recommend to find an optimal {{TAG\|POTIM}} using {{TAG\|IBRION}}=2 or performing a few test calculations (see below).

← Older revision		Revision as of 10:07, 17 February 2025
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	:::** {{TAG\|IBRION}}=44 [[improved dimer method]]		:::** {{TAG\|IBRION}}=44 [[improved dimer method]]

	:::* [[#~~User-~~supplied ~~interactive changes~~\|User-supplied interactive changes]]		:::* [[#Interactively supplied positions and lattice vectors\|User-supplied interactive changes]]
	:::** {{TAG\|IBRION}}=11 from standard input		:::** {{TAG\|IBRION}}=11 from standard input
	:::** {{TAG\|IBRION}}=12 from Python plugin		:::** {{TAG\|IBRION}}=12 from Python plugin

← Older revision		Revision as of 11:05, 7 January 2025
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	[[IRC calculations]],		[[IRC calculations]],
	[[Improved Dimer Method]],		[[Improved Dimer Method]],
	[[Writing a Python plugin]]		[[Plugins\|Writing a Python plugin]]

	{{sc\|IBRION\|Examples\|Examples that use this tag}}		{{sc\|IBRION\|Examples\|Examples that use this tag}}

	[[Category:INCAR tag]][[Category:Ionic minimization]][[Category:Molecular dynamics]][[Category:Phonons]][[Category:Transition states]]		[[Category:INCAR tag]][[Category:Ionic minimization]][[Category:Molecular dynamics]][[Category:Phonons]][[Category:Transition states]]

← Older revision		Revision as of 08:29, 10 July 2024
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	#If {{TAG\|NFREE}} is not specified, the criterion whether information is removed from the iteration history is based on the eigenvalue spectrum of the inverse Hessian matrix: if one eigenvalue of the inverse Hessian matrix is larger than 8, information from previous steps is discarded.		#If {{TAG\|NFREE}} is not specified, the criterion whether information is removed from the iteration history is based on the eigenvalue spectrum of the inverse Hessian matrix: if one eigenvalue of the inverse Hessian matrix is larger than 8, information from previous steps is discarded.

	For complex problems {{TAG\|NFREE}} can usually be set to a rather large value (i.e. 10-20), however systems of low dimensionality require a ~~carful~~ setting of {{TAG\|NFREE}} (or preferably an exact counting of the number of degrees of freedom). To increase {{TAG\|NFREE}} beyond 20 rarely improves convergence. If {{TAG\|NFREE}} is set to too large, the RMM-DIIS algorithm might diverge.		For complex problems {{TAG\|NFREE}} can usually be set to a rather large value (i.e. 10-20), however systems of low dimensionality require a careful setting of {{TAG\|NFREE}} (or preferably an exact counting of the number of degrees of freedom). To increase {{TAG\|NFREE}} beyond 20 rarely improves convergence. If {{TAG\|NFREE}} is set to too large, the RMM-DIIS algorithm might diverge.

	The choice of a reasonable {{TAG\|POTIM}} is also important and can speed up calculations significantly, we recommend to find an optimal {{TAG\|POTIM}} using {{TAG\|IBRION}}=2 or performing a few test calculations (see below).		The choice of a reasonable {{TAG\|POTIM}} is also important and can speed up calculations significantly, we recommend to find an optimal {{TAG\|POTIM}} using {{TAG\|IBRION}}=2 or performing a few test calculations (see below).

← Older revision		Revision as of 07:44, 24 October 2025
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	Description: determines how the crystal structure changes during the calculation:		Description: determines how the crystal structure changes during the calculation:
	:::* no update		:::* no update
	:::** {{TAG\|IBRION}}~~=-1~~ (Avoid setting {{TAG\|IBRION}}~~=-1~~ with {{TAG\|NSW}}>0 to prevent recomputing the same structure {{TAG\|NSW}} times).		:::** {{TAG\|IBRION\|-1}} (Avoid setting {{TAG\|IBRION\|-1}} with {{TAG\|NSW\|0\|op=>}} to prevent recomputing the same structure {{TAG\|NSW}} times).

	:::* [[#Molecular dynamics\|Molecular dynamics]]		:::* [[#Molecular dynamics\|Molecular dynamics]]
	:::** {{TAG\|IBRION}}=0		:::** {{TAG\|IBRION\|0}}

	:::* [[#Structure optimization\|Structure optimization]]		:::* [[#Structure optimization\|Structure optimization]]
	:::** {{TAG\|IBRION}}=1 RMM-DIIS		:::** {{TAG\|IBRION\|1}} RMM-DIIS
	:::** {{TAG\|IBRION}}=2 conjugate gradient		:::** {{TAG\|IBRION\|2}} conjugate gradient
	:::** {{TAG\|IBRION}}=3 damped molecular dynamics		:::** {{TAG\|IBRION\|3}} damped molecular dynamics

	:::* [[#Computing the phonon modes\|Computing phonon modes]]		:::* [[#Computing the phonon modes\|Computing phonon modes]]
	:::** {{TAG\|IBRION}}=5 finite differences without symmetry		:::** {{TAG\|IBRION\|5}} finite differences without symmetry
	:::** {{TAG\|IBRION}}=6 finite differences with symmetry		:::** {{TAG\|IBRION\|6}} finite differences with symmetry
	:::** {{TAG\|IBRION}}=7 perturbation theory without symmetry		:::** {{TAG\|IBRION\|7}} perturbation theory without symmetry
	:::** {{TAG\|IBRION}}=8 perturbation theory with symmetry		:::** {{TAG\|IBRION\|8}} perturbation theory with symmetry

	:::* [[#Analyzing transition states\|Analyzing transition states]]		:::* [[#Analyzing transition states\|Analyzing transition states]]
	:::** {{TAG\|IBRION}}~~=40~~ [[IRC calculations\|intrinsic-reaction-coordinate calculations]]		:::** {{TAG\|IBRION\|40}} [[IRC calculations\|intrinsic-reaction-coordinate calculations]]
	:::** {{TAG\|IBRION}}~~=44~~ [[improved dimer method]]		:::** {{TAG\|IBRION\|44}} [[improved dimer method]]

	:::* [[#Interactively supplied positions and lattice vectors\|User-supplied interactive changes]]		:::* [[#Interactively supplied positions and lattice vectors\|User-supplied interactive changes]]
	:::** {{TAG\|IBRION}}~~=11~~ from standard input		:::** {{TAG\|IBRION\|11}} from standard input
	:::** {{TAG\|IBRION}}~~=12~~ from Python plugin		:::** {{TAG\|IBRION\|12}} from Python plugin

	----		----
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	To find the solution, VASP provides multiple algorithms:		To find the solution, VASP provides multiple algorithms:

	* RMM-DIIS ({{TAG\|IBRION}}=1) reduces the forces by linear combination of previous positions. It is the method of choice for larger systems (>20 degrees of freedom) that are reasonably close to the ground-state structure.		* RMM-DIIS ({{TAG\|IBRION\|1}}) reduces the forces by linear combination of previous positions. It is the method of choice for larger systems (>20 degrees of freedom) that are reasonably close to the ground-state structure.
	* Conjugate gradient ({{TAG\|IBRION}}=2) finds the optimal step size along a search direction. It is a robust default choice but may need more iterations than RMM-DIIS.		* Conjugate gradient ({{TAG\|IBRION\|2}}) finds the optimal step size along a search direction. It is a robust default choice but may need more iterations than RMM-DIIS.
	* Damped molecular dynamics ({{TAG\|IBRION}}=3) runs a MD simulation with decreasing velocity of the ions. Use this for large systems far away from the minimum to get to a better starting point for the other algorithms.		* Damped molecular dynamics ({{TAG\|IBRION\|3}}) runs a MD simulation with decreasing velocity of the ions. Use this for large systems far away from the minimum to get to a better starting point for the other algorithms.

	Consult the [[structure optimization]] page for advise on how to choose the optimization algorithm.		Consult the [[structure optimization]] page for advise on how to choose the optimization algorithm.
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	The second-order derivatives of the total energy <math>E</math> with respect to ionic positions <math>R_{\alpha i}</math> of ion <math>\alpha</math> in the direction <math>i</math>, is computed using a first-order derivative of the [[forces]] <math>F_{\beta j}</math>. Then, the dynamical matrix <math>D_{\alpha i \beta j}</math> is constructed, diagonalized, and the phonon modes and frequencies of the system are reported in the {{FILE\|OUTCAR}} file and {{FILE\|vaspout.h5}}. Also see [[Phonons: Theory\|theory on phonons]].		The second-order derivatives of the total energy <math>E</math> with respect to ionic positions <math>R_{\alpha i}</math> of ion <math>\alpha</math> in the direction <math>i</math>, is computed using a first-order derivative of the [[forces]] <math>F_{\beta j}</math>. Then, the dynamical matrix <math>D_{\alpha i \beta j}</math> is constructed, diagonalized, and the phonon modes and frequencies of the system are reported in the {{FILE\|OUTCAR}} file and {{FILE\|vaspout.h5}}. Also see [[Phonons: Theory\|theory on phonons]].
	{{NB\|tip\|It may be necessary to set {{~~TAGO~~\|EDIFF\|<= 1E-6}} because the default ({{~~TAGO~~\|EDIFF\|1E-4}}) often results in unacceptably large errors.}}		{{NB\|tip\|It may be necessary to set {{TAG\|EDIFF\|1E-6\|op=<=}} because the default ({{TAG\|EDIFF\|1E-4}}) often results in unacceptably large errors.}}
	VASP implements two different methods to compute the phonon modes and can use symmetry to reduce the number of computed displacements:		VASP implements two different methods to compute the phonon modes and can use symmetry to reduce the number of computed displacements:

	* {{~~TAGO~~\|IBRION\|5}} [[Phonons from finite differences\|finite differences]] '''without''' symmetry		* {{TAG\|IBRION\|5}} [[Phonons from finite differences\|finite differences]] '''without''' symmetry
	* {{~~TAGO~~\|IBRION\|6}} [[Phonons from finite differences\|finite differences]] '''with''' symmetry		* {{TAG\|IBRION\|6}} [[Phonons from finite differences\|finite differences]] '''with''' symmetry
	* {{~~TAGO~~\|IBRION\|7}} [[Phonons_from_density-functional-perturbation_theory\|density-functional-perturbation theory]] '''without''' symmetry		* {{TAG\|IBRION\|7}} [[Phonons_from_density-functional-perturbation_theory\|density-functional-perturbation theory]] '''without''' symmetry
	* {{~~TAGO~~\|IBRION\|8}} [[Phonons_from_density-functional-perturbation_theory\|density-functional-perturbation theory]] '''with''' symmetry		* {{TAG\|IBRION\|8}} [[Phonons_from_density-functional-perturbation_theory\|density-functional-perturbation theory]] '''with''' symmetry

	For finite differences, the elastic tensors and internal strain tensors is computed for {{TAG\|ISIF}}~~>=3~~.		For finite differences, the elastic tensors and internal strain tensors is computed for {{TAG\|ISIF\|3\|op=>=}}.
	Compute Born-effective charges, piezoelectric constants, and the ionic contribution to the dielectric tensor by specifying {{~~TAGO~~\|LEPSILON\|.TRUE.}} ([[Linear response\|linear response theory]]) or {{~~TAGO~~\|LCALCEPS\|.TRUE.}} (finite external field).		Compute Born-effective charges, piezoelectric constants, and the ionic contribution to the dielectric tensor by specifying {{TAG\|LEPSILON\|.TRUE.}} ([[Linear response\|linear response theory]]) or {{TAG\|LCALCEPS\|.TRUE.}} (finite external field).

	Also see [[computing the phonon dispersion and DOS]].		Also see [[computing the phonon dispersion and DOS]].
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	For the analysis of transition states the following methods are available:		For the analysis of transition states the following methods are available:

	* Setting {{~~TAGO~~\|IBRION\|40}}, you can start from a transition state and monitor the energy along an intrinsic-reaction coordinate (IRC). The [[IRC calculations]] section describes this method.		* Setting {{TAG\|IBRION\|40}}, you can start from a transition state and monitor the energy along an intrinsic-reaction coordinate (IRC). The [[IRC calculations]] section describes this method.
	* With the [[improved dimer method]] ({{~~TAGO~~\|IBRION\|44}}), you can search for a the transition state starting from an arbitrary structure in the investigated phase space.		* With the [[improved dimer method]] ({{TAG\|IBRION\|44}}), you can search for a the transition state starting from an arbitrary structure in the investigated phase space.
	* The [[nudged elastic bands]] method finds an approximate reaction path based on the initial and final structure, i.e., reactant and product.		* The [[nudged elastic bands]] method finds an approximate reaction path based on the initial and final structure, i.e., reactant and product.

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	In these scenarios, VASP provides the following alternatives		In these scenarios, VASP provides the following alternatives

	* With {{~~TAGO~~\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF}}~~>=3~~, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.		* With {{TAG\|IBRION\|11}}, you can provide new structures via the standard input. For {{TAG\|ISIF\|3\|op=>=}}, a complete {{FILE\|POSCAR}} file is read, otherwise just the positions in fractional coordinates.

	* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Plugins\|write a Python plugin]] to modify the structure. Set {{~~TAGO~~\|IBRION\|12}} or {{~~TAGO~~\|PLUGINS/STRUCTURE\|T}} to activate it.		* If you [[Makefile.include#Plugins_(optional)\|linked VASP with Python]], you can [[Plugins\|write a Python plugin]] to modify the structure. Set {{TAG\|IBRION\|12}} or {{TAG\|PLUGINS/STRUCTURE\|T}} to activate it.

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