ISIF - Revision history

Schlipf: /* Related tags and articles */

2024-10-18T11:49:15Z

Huebsch: /* Related tags and articles */

2024-07-01T06:59:22Z

Mani: Use more TAGO

2024-02-06T16:05:41Z

Use more TAGO

← Older revision		Revision as of 16:05, 6 February 2024
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	{{TAGDEF\|ISIF\|0 {{!}} 1 {{!}} 2 {{!}} 3 {{!}} 4 {{!}} 5 {{!}} 6 {{!}} 7 {{!}} 8}}		{{TAGDEF\|ISIF\|0 {{!}} 1 {{!}} 2 {{!}} 3 {{!}} 4 {{!}} 5 {{!}} 6 {{!}} 7 {{!}} 8}}
	{{DEF\|ISIF\|0\|for {{~~TAG~~\|IBRION}}~~{{=}}0~~ (molecular dynamics) or {{~~TAG~~\|LHFCALC~~}}{{=}}~~.TRUE.\|2\|else}}		{{DEF\|ISIF\|0\|for {{TAGO\|IBRION\|0}} (molecular dynamics) or {{TAGO\|LHFCALC\|.TRUE.}}\|2\|else}}

	Description: Determines if the stress tensor is calculated and which ionic degrees of freedom are varied.		Description: Determines if the stress tensor is calculated and which ionic degrees of freedom are varied.

Mani: Fix broken wiki links and use TAGO template

2024-02-06T15:51:06Z

Fix broken wiki links and use TAGO template

← Older revision		Revision as of 15:51, 6 February 2024
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	\|}		\|}

	* For {{~~TAG~~\|ISIF}}=1, only the trace of the stress tensor is calculated. This means only the total pressure is correct and can be read off in the line:		* For {{TAGO\|ISIF\|1}}, only the trace of the stress tensor is calculated. This means only the total pressure is correct and can be read off in the line:

	external pressure = ... kB		external pressure = ... kB
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	:The individual components of the stress tensor are not reliable in this case and must be disregarded.		:The individual components of the stress tensor are not reliable in this case and must be disregarded.
	* Accuracy		* Accuracy
	{{NB\|warning\|The PAW basis for the [[Category:Electronic minimization\|electronic minimization]] is not adjusted when the structure is varied during a calculation.\|:}}		{{NB\|warning\|The PAW basis for the [[:Category:Electronic minimization\|electronic minimization]] is not adjusted when the structure is varied during a calculation.\|:}}
	:Therefore, carefully consider effects such as [[Energy_vs_volume_Volume_relaxations_and Pulay_stress\|Pulay stress]] and choose generous settings for the [[Category:Electronic minimization\|electronic minimization]]. Generally, volume changes should be done only with an increased energy cutoff, e.g., {{~~TAG~~\|ENCUT~~}}{{=}}~~1.3×max({{TAG\|ENMAX}}), and {{~~TAG~~\|PREC}}~~{{=}}High~~.		:Therefore, carefully consider effects such as [[Energy_vs_volume_Volume_relaxations_and Pulay_stress\|Pulay stress]] and choose generous settings for the [[:Category:Electronic minimization\|electronic minimization]]. Generally, volume changes should be done only with an increased energy cutoff, e.g., {{TAGO\|ENCUT\|1.3×max({{TAG\|ENMAX}})}}, and {{TAGO\|PREC\|High}}.
	* To further control the ionic degrees of freedom that can vary during the calculation, set `Selective dynamics` in the {{FILE\|POSCAR}} file.		* To further control the ionic degrees of freedom that can vary during the calculation, set `Selective dynamics` in the {{FILE\|POSCAR}} file.
	* ~~ISIF~~{{=}}8 is only available as of VASP.6.4.1.		* {{TAGO\|ISIF\|8}} is only available as of VASP.6.4.1.
	== Related tags and articles ==		== Related tags and articles ==
	{{TAG\|IBRION}},		{{TAG\|IBRION}},

Huebsch at 17:28, 27 October 2023

2023-10-27T17:28:33Z

← Older revision		Revision as of 17:28, 27 October 2023
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	For {{TAG\|ISIF}}<math>\ge</math>2, the stress tensor is calculated. It is defined as the negative of the derivative of the energy		For {{TAG\|ISIF}}<math>\ge</math>2, the stress tensor is calculated. It is defined as the negative of the derivative of the energy
	<math> E </math> with respect to the strain tensor <math>\~~epsilon_~~{ji}</math>:		<math> E </math> with respect to the strain tensor <math>\eta_{ji}</math>:

	:<math> \sigma_{ij} = - \frac{\delta E} {\delta \~~epsilon_~~{ji}} </math>.		:<math> \sigma_{ij} = - \frac{\delta E} {\delta \eta_{ji}} </math>.

	This might be different from other first principles codes.		This might be different from other first principles codes.

Huebsch at 08:14, 24 October 2023

2023-10-24T08:14:51Z

← Older revision		Revision as of 08:14, 24 October 2023
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	<math> E </math> with respect to the strain tensor <math>\epsilon_{ji}</math>:		<math> E </math> with respect to the strain tensor <math>\epsilon_{ji}</math>:

	:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>		:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>.

	This might be different from other first principles codes.		This might be different from other first principles codes.

Huebsch at 08:14, 24 October 2023

2023-10-24T08:14:33Z

← Older revision		Revision as of 08:14, 24 October 2023
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	For {{TAG\|ISIF}}<math>\ge</math>2, the stress tensor is calculated. It is defined as the negative of the derivative of the energy		For {{TAG\|ISIF}}<math>\ge</math>2, the stress tensor is calculated. It is defined as the negative of the derivative of the energy
	<math> E </math>		<math> E </math> with respect to the strain tensor <math>\epsilon_{ji}</math>:
	with respect to the strain tensor <math> \epsilon_{ji} </math>:

	:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>		:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>

Huebsch at 08:14, 24 October 2023

2023-10-24T08:14:09Z

← Older revision		Revision as of 08:14, 24 October 2023
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	For {{TAG\|ISIF}}<math>\ge</math>2, the stress tensor is calculated. It is defined as the negative of the derivative of the energy		For {{TAG\|ISIF}}<math>\ge</math>2, the stress tensor is calculated. It is defined as the negative of the derivative of the energy
	<math> E </math>		<math> E </math>
	with respect to the strain tensor <math> \epsilon_{ij} </math>:		with respect to the strain tensor <math> \epsilon_{ji} </math>:

	:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>		:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>

Huebsch at 08:13, 24 October 2023

2023-10-24T08:13:26Z

← Older revision		Revision as of 08:13, 24 October 2023
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	with respect to the strain tensor <math> \epsilon_{ij} </math>:		with respect to the strain tensor <math> \epsilon_{ij} </math>:

	:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ij}} </math>		:<math> \sigma_{ij} = - \frac{\delta E} {\delta \epsilon_{ji}} </math>

	This might be different from other first principles codes.		This might be different from other first principles codes.
	A positive in the diagonals means that the system is under compressive strain and wants to expand. A negative value implies that the system is under tensile strain and wants to reduce its volume.		A positive in the diagonals means that the system is under compressive strain and wants to expand. A negative value implies that the system is under tensile strain and wants to reduce its volume. The stress tensor is symmetric <math>\sigma_{ij}=\sigma_{ji}</math>, and, thus, it has six independent entries.
	The calculation of the stress tensor is relatively time-consuming, and, therefore, by default, it is switched off in some cases. The forces are always calculated.		The calculation of the stress tensor is relatively time-consuming, and, therefore, by default, it is switched off in some cases. The forces are always calculated.

Ftran at 08:23, 20 October 2023

2023-10-20T08:23:14Z

← Older revision		Revision as of 08:23, 20 October 2023
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	----		----
	~~[[The_VASP_Manual\|Contents]]~~

	[[Category:INCAR tag]][[Category:Ionic minimization]][[Category:Molecular dynamics]][[Category:Symmetry]]		[[Category:INCAR tag]][[Category:Ionic minimization]][[Category:Molecular dynamics]][[Category:Symmetry]]

← Older revision		Revision as of 11:49, 18 October 2024
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	== Related tags and articles ==		== Related tags and articles ==
	{{TAG\|IBRION}},		{{TAG\|IBRION}},
			[[structure optimization]],
	[[:Category:Ensembles\| Ensembles]],		[[:Category:Ensembles\| Ensembles]],
	Selective-dynamics mode of the {{FILE\|POSCAR}} file,		Selective-dynamics mode of the {{FILE\|POSCAR}} file,

← Older revision		Revision as of 06:59, 1 July 2024
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	{{TAG\|IBRION}},		{{TAG\|IBRION}},
	[[:Category:Ensembles\| Ensembles]],		[[:Category:Ensembles\| Ensembles]],
	Selective-dynamics mode of the {{FILE\|POSCAR}} file		Selective-dynamics mode of the {{FILE\|POSCAR}} file,
			{{TAG\|LATTICE_CONSTRAINTS}}

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