GGA COMPAT - Revision history

Liebetreu at 14:17, 14 October 2025

2025-10-14T14:17:15Z

← Older revision		Revision as of 14:17, 14 October 2025
Line 9:		Line 9:
	The origin of this problem is subtle and relates to the fact that the gradient field breaks the lattice symmetry for noncubic lattices. This can be fixed by setting		The origin of this problem is subtle and relates to the fact that the gradient field breaks the lattice symmetry for noncubic lattices. This can be fixed by setting
	GGA_COMPAT = .FALSE.		GGA_COMPAT = .FALSE.
	to apply a spherical cutoff to the gradient field. In other words, the gradient field, as well as the charge density are set to zero for all reciprocal lattice vectors <math>\~~bold~~{G}</math> that exceed a certain cutoff length		to apply a spherical cutoff to the gradient field. In other words, the gradient field, as well as the charge density are set to zero for all reciprocal lattice vectors <math>\mathbf{G}</math> that exceed a certain cutoff length
	<math>\~~bold~~{G}_{cut}</math> before calculating the exchange-correlation energy and potential.		<math>\mathbf{G}_{cut}</math> before calculating the exchange-correlation energy and potential.
	The cutoff <math>\~~bold~~{G}_{cut}</math> is determined automatically so that the cutoff sphere is fully inscribed in the parallelepiped defined by the FFT grid in reciprocal space.		The cutoff <math>\mathbf{G}_{cut}</math> is determined automatically so that the cutoff sphere is fully inscribed in the parallelepiped defined by the FFT grid in reciprocal space.
	{{NB\|mind\| For compatibility reasons with older versions of VASP, the default is {{TAG\|GGA_COMPAT}}{{=}}''.TRUE.'' However, setting the tag usually changes the energy only in the sub-meV energy range (0.1 meV), and for most results the setting of {{TAG\|GGA_COMPAT}} is insignificant. The most important exception is for the calculation of magnetic anisotropy, for which we strongly recommend {{TAG\|GGA_COMPAT}}{{=}}.''FALSE''.\|:}}		{{NB\|mind\| For compatibility reasons with older versions of VASP, the default is {{TAG\|GGA_COMPAT}}{{=}}''.TRUE.'' However, setting the tag usually changes the energy only in the sub-meV energy range (0.1 meV), and for most results the setting of {{TAG\|GGA_COMPAT}} is insignificant. The most important exception is for the calculation of magnetic anisotropy, for which we strongly recommend {{TAG\|GGA_COMPAT}}{{=}}.''FALSE''.\|:}}
	== Related tags and articles ==		== Related tags and articles ==

Ftran at 15:20, 27 February 2025

2025-02-27T15:20:37Z

← Older revision		Revision as of 15:20, 27 February 2025
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	----		----

	[[Category:INCAR tag]][[Category:Exchange-correlation functionals~~]][[Category:GGA~~]][[Category:Symmetry]]		[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Symmetry]]

Huebsch at 05:50, 20 October 2023

2023-10-20T05:50:42Z

← Older revision		Revision as of 05:50, 20 October 2023
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	{{TAGDEF\|GGA_COMPAT\|.TRUE. {{!}} .FALSE. \|.TRUE.}}		{{TAGDEF\|GGA_COMPAT\|.TRUE. {{!}} .FALSE. \|.TRUE.}}

	Description: If set to {{TAG\|GGA_COMPAT}} = .''FALSE''., this ~~flag~~ restores the full lattice symmetry for gradient corrected functionals.		Description: If set to {{TAG\|GGA_COMPAT}} = .''FALSE''., this tag restores the full lattice symmetry for gradient-corrected functionals.
	----		----

	{{TAG\|GGA}} and {{TAG\|METAGGA}} functionals might break the symmetry of		{{TAG\|GGA}} and {{TAG\|METAGGA}} functionals might break the symmetry of
	the Bravais lattice slightly for ~~non~~ cubic cells ~~(this~~		the Bravais lattice slightly for cells that are not primitive cubic cells.
	~~includes primitive fcc and bcc lattices)~~.		The origin of this problem is subtle and relates to the fact that the gradient field breaks the lattice symmetry for noncubic lattices. This can be fixed by setting
	The origin of this problem is subtle and relates to the fact that the gradient
	field breaks the lattice symmetry for ~~non-cubic~~ lattices. This can be fixed by setting
	GGA_COMPAT = .FALSE.		GGA_COMPAT = .FALSE.
	to apply a spherical cutoff to the gradient field,		to apply a spherical cutoff to the gradient field. In other words, the gradient field, as well as the charge density are set to zero for all reciprocal lattice vectors <math>\bold{G}</math> that exceed a certain cutoff length
	~~i.e.~~ for all reciprocal lattice vectors <math>\bold{G}</math> that exceed a certain cutoff length		<math>\bold{G}_{cut}</math> before calculating the exchange-correlation energy and potential.
	<math>\bold{G}_{cut}</math> ~~the gradient field as well as the charge density are set to~~		The cutoff <math>\bold{G}_{cut}</math> is determined automatically so that the cutoff sphere is fully inscribed in the parallelepiped defined by the FFT grid in reciprocal space.
	~~zero~~ before calculating the exchange correlation energy and potential.		{{NB\|mind\| For compatibility reasons with older versions of VASP, the default is {{TAG\|GGA_COMPAT}}{{=}}''.TRUE.'' However, setting the tag usually changes the energy only in the sub-meV energy range (0.1 meV), and for most results the setting of {{TAG\|GGA_COMPAT}} is insignificant. The most important exception is for the calculation of magnetic anisotropy, for which we strongly recommend {{TAG\|GGA_COMPAT}}{{=}}.''FALSE''.\|:}}
	The cutoff <math>\bold{G}_{cut}</math> is determined automatically so that the cutoff sphere
	is fully inscribed in the parallelepiped defined by the FFT grid in ~~the~~ reciprocal space.

	{{NB\|mind\| For compatibility reasons with older versions of VASP, the default is {{TAG\|GGA_COMPAT}}{{=}}''.TRUE.'' However, setting the ~~flag~~ usually changes the energy only in the sub meV energy range (0.1 meV), and for most results ~~it does matter little how~~ {{TAG\|GGA_COMPAT}} is ~~set~~. The most important exception is for the calculation of magnetic anisotropy, for which we strongly recommend {{TAG\|GGA_COMPAT}}{{=}}.''FALSE''.\|:}}

	== Related tags and articles ==		== Related tags and articles ==
	{{TAG\|GGA}},		{{TAG\|GGA}},
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	----		----

	[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]]		[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]][[Category:Symmetry]]

Ftran at 15:11, 18 October 2023

2023-10-18T15:11:20Z

← Older revision		Revision as of 15:11, 18 October 2023
Line 5:		Line 5:
	----		----

	~~Gradient corrected~~ functionals might break the symmetry of		{{TAG\|GGA}} and {{TAG\|METAGGA}} functionals might break the symmetry of
	the Bravais lattice slightly for non cubic cells (this		the Bravais lattice slightly for non cubic cells (this
	includes primitive fcc and bcc lattices).		includes primitive fcc and bcc lattices).

Ftran at 12:22, 18 October 2023

2023-10-18T12:22:49Z

← Older revision		Revision as of 12:22, 18 October 2023
Line 2:		Line 2:
	{{TAGDEF\|GGA_COMPAT\|.TRUE. {{!}} .FALSE. \|.TRUE.}}		{{TAGDEF\|GGA_COMPAT\|.TRUE. {{!}} .FALSE. \|.TRUE.}}

	Description: ~~This~~ flag restores the full lattice symmetry for gradient corrected functionals.		Description: If set to {{TAG\|GGA_COMPAT}} = .''FALSE''., this flag restores the full lattice symmetry for gradient corrected functionals.
	----		----

	~~For gradient~~ corrected functionals ~~the~~		Gradient corrected functionals might break the symmetry of
	~~exchange correlation functional~~ might break the symmetry of
	the Bravais lattice slightly for non cubic cells (this		the Bravais lattice slightly for non cubic cells (this
	includes primitive fcc and bcc lattices).		includes primitive fcc and bcc lattices).
	The origin of this problem is subtle and relates to the fact that the gradient		The origin of this problem is subtle and relates to the fact that the gradient
	field breaks the lattice symmetry for non-cubic lattices.		field breaks the lattice symmetry for non-cubic lattices. This can be fixed by setting
	~~To fix this,~~ a spherical cutoff ~~is applied~~ to the gradient field		GGA_COMPAT = .FALSE.
	~~for {{TAG\|GGA_COMPAT}} = .''FALSE''~~.,		to apply a spherical cutoff to the gradient field,
	e.g. for all reciprocal lattice vectors <math>\bold{G}</math> that exceed a certain cutoff length		i.e. for all reciprocal lattice vectors <math>\bold{G}</math> that exceed a certain cutoff length
	<math>\bold{G}_{cut}</math> the gradient field as well as the charge density is set to		<math>\bold{G}_{cut}</math> the gradient field as well as the charge density are set to
	zero before calculating the exchange correlation energy and potential.		zero before calculating the exchange correlation energy and potential.
	The cutoff <math>\bold{G}_{cut}</math> is determined automatically so that the cutoff sphere		The cutoff <math>\bold{G}_{cut}</math> is determined automatically so that the cutoff sphere
	is fully inscribed in the parallelepiped defined by the FFT grid in		is fully inscribed in the parallelepiped defined by the FFT grid in the reciprocal space.
	the reciprocal space.

	~~Since this flag restores the full lattice symmetry for gradient corrected functionals,~~		{{NB\|mind\| For compatibility reasons with older versions of VASP, the default is {{TAG\|GGA_COMPAT}}{{=}}''.TRUE.'' However, setting the flag usually changes the energy only in the sub meV energy range (0.1 meV), and for most results it does matter little how {{TAG\|GGA_COMPAT}} is set. The most important exception is for the calculation of magnetic anisotropy, for which we strongly recommend {{TAG\|GGA_COMPAT}}{{=}}.''FALSE''.\|:}}
	~~and we therefore recommend to set~~
	~~GGA_COMPAT = .FALSE.~~
	~~for all gradient corrected calculations.~~ For compatibility reasons,
	the default is {{TAG\|GGA_COMPAT}} = ''.TRUE.'' ~~until VASP.5.2.~~
	However, setting the flag usually changes the energy only in the sub meV energy range
	(0.1 meV), and for most results it does matter little how
	{{TAG\|GGA_COMPAT}} is set. The most important exception ~~are~~ magnetic
	~~anisotropies~~, for which we strongly recommend ~~to set~~ {{TAG\|GGA_COMPAT}} = .''FALSE''.

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

Ftran at 12:43, 8 April 2022

2022-04-08T12:43:20Z

← Older revision		Revision as of 12:43, 8 April 2022
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	{{sc\|GGA_COMPAT\|Examples\|Examples that use this tag}}		{{sc\|GGA_COMPAT\|Examples\|Examples that use this tag}}
	----		----
	~~[[The_VASP_Manual\|Contents]]~~

	[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]]		[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]]

Karsai at 06:47, 7 April 2022

2022-04-07T06:47:20Z

← Older revision		Revision as of 06:47, 7 April 2022
Line 38:		Line 38:
	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR ~~tags~~]][[Category:Exchange-correlation functionals]][[Category:GGA]]		[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:GGA]]

Karsai at 16:40, 6 April 2022

2022-04-06T16:40:59Z

← Older revision		Revision as of 16:40, 6 April 2022
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	anisotropies, for which we strongly recommend to set {{TAG\|GGA_COMPAT}} = .''FALSE''.		anisotropies, for which we strongly recommend to set {{TAG\|GGA_COMPAT}} = .''FALSE''.

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|GGA}},		{{TAG\|GGA}},
	{{TAG\|METAGGA}}		{{TAG\|METAGGA}}
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	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR]][[Category:Exchange-correlation functionals]][[Category:GGA]]		[[Category:INCAR tags]][[Category:Exchange-correlation functionals]][[Category:GGA]]

Ftran at 08:05, 6 April 2022

2022-04-06T08:05:33Z

← Older revision		Revision as of 08:05, 6 April 2022
Line 38:		Line 38:
	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR]][[Category:~~XC Functionals~~]][[Category:GGA]]		[[Category:INCAR]][[Category:Exchange-correlation functionals]][[Category:GGA]]

Ftran at 08:28, 19 January 2022

2022-01-19T08:28:37Z

← Older revision		Revision as of 08:28, 19 January 2022
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			{{DISPLAYTITLE:GGA_COMPAT}}
	{{TAGDEF\|GGA_COMPAT\|.TRUE. {{!}} .FALSE. \|.TRUE.}}		{{TAGDEF\|GGA_COMPAT\|.TRUE. {{!}} .FALSE. \|.TRUE.}}