NMAXFOCKAE and LMAXFOCKAE - Revision history

Kresse at 12:17, 29 March 2023

2023-03-29T12:17:31Z

Kresse at 12:14, 29 March 2023

2023-03-29T12:14:54Z

← Older revision		Revision as of 12:14, 29 March 2023
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	To achieve the improved treatment on the plane wave grid, <math> Q_{\alpha\beta}({\mathbf r}) </math> is Fourier transformed to reciprocal space <math> Q_{\alpha\beta}(q) </math> and then expanded		To achieve the improved treatment on the plane wave grid, <math> Q_{\alpha\beta}({\mathbf r}) </math> is Fourier transformed to reciprocal space <math> Q_{\alpha\beta}(q) </math> and then expanded
	in a set of orthogonal functions localized at each atomic site. These augmentation charges		in a set of orthogonal functions localized at each atomic site. These augmentation charges
	are then added to the pseudo charge densities on the plane wave grid.		are then added to the pseudo charge densities on the plane wave grid. Shape restoration is only accurate up to a certain plane wave cutoff, typically about 150 eV for '''NMAXFOCKAE''' =1, and 400 eV for '''NMAXFOCKAE''' = 2. Experiences shows, that '''NMAXFOCKAE''' =1 is sufficient to predict very accurate energy differences, and quite accurate quasiparticle energies.

Kresse at 12:08, 29 March 2023

2023-03-29T12:08:55Z

← Older revision		Revision as of 12:08, 29 March 2023
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	This allows to restore the all-electron densities accurately already on the plane wave grid		This allows to restore the all-electron densities accurately already on the plane wave grid
	by specifying the flags '''LMAXFOCKAE''' and '''NMAXFOCKAE'''. This improved		by specifying the flags '''LMAXFOCKAE''' and '''NMAXFOCKAE'''. This improved
	~~treatment-~~ termed shape restoration ~~-is~~ available for exchange as well as many body correlation contributions.		treatment— termed shape restoration —is available for exchange as well as many body correlation contributions.
	For exchange, the exact one-center terms are also implemented. This means shape restoration is not required and should not change the results.		For exchange, the exact one-center terms are also implemented. This means shape restoration is not required and should not change the results.

Tal at 11:59, 29 March 2023

2023-03-29T11:59:32Z

← Older revision		Revision as of 11:59, 29 March 2023
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	should test whether '''LMAXFOCKAE'''= 6 is required.		should test whether '''LMAXFOCKAE'''= 6 is required.

	More details on shape restoration are explained in M. ~~Shishkin and G. Kresse, Phys. Rev. B 74, 035101 (~~2006) and M. ~~Unzog ,A. Tal, and G. Kresse, Phys. Rev. B106,155133(2022)~~		More details on shape restoration are explained in Ref.{{cite\|shishkin:prb:2006}} and {{cite\|unzog:prb:2022}}.

	== Usefull Settings ==		== Usefull Settings ==

Kresse: References added

2023-03-29T10:37:13Z

References added

← Older revision		Revision as of 10:37, 29 March 2023
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	Description: '''NMAXFOCKAE''' and '''LMAXFOCKAE''' determine whether		Description: '''NMAXFOCKAE''' and '''LMAXFOCKAE''' determine whether
	the overlap densities in the Fock exchange and correlated wave function methods are accurately reconstructed on the plane wave grid. This flag generally only applies to the Fock-exchange part as well as many-body		the overlap densities in the Fock exchange and correlated wave function methods are accurately reconstructed on the plane wave grid (shape restoration). This flag generally only applies to the Fock-exchange part as well as many-body
	post DFT methods (GW, RPA, MP2, etc.).		post DFT methods (GW, RPA, MP2, etc.).
	----		----
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	This allows to restore the all-electron densities accurately already on the plane wave grid		This allows to restore the all-electron densities accurately already on the plane wave grid
	by specifying the flags '''LMAXFOCKAE''' and '''NMAXFOCKAE'''. This improved		by specifying the flags '''LMAXFOCKAE''' and '''NMAXFOCKAE'''. This improved
	treatment is available for exchange as well as many body correlation contributions.		treatment- termed shape restoration -is available for exchange as well as many body correlation contributions.
	For exchange, the one-center terms are also implemented, and ~~if the improved~~		For exchange, the exact one-center terms are also implemented. This means shape restoration is not required and should not change the results.
	~~treatment is selected on the plane wave grid, the pseudo-densities on the radial~~
	~~grids are treated in the same (improved) manner as on~~ the ~~plane wave grid~~.

	To achieve the improved treatment on the plane wave grid, <math> Q_{\alpha\beta}({\mathbf r}) </math> is Fourier transformed to reciprocal space <math> Q_{\alpha\beta}(q) </math> and then expanded		To achieve the improved treatment on the plane wave grid, <math> Q_{\alpha\beta}({\mathbf r}) </math> is Fourier transformed to reciprocal space <math> Q_{\alpha\beta}(q) </math> and then expanded
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	(a d electron can create charge densities with ''L''-quantum numbers up to 4), whereas for f elements, users		(a d electron can create charge densities with ''L''-quantum numbers up to 4), whereas for f elements, users
	should test whether '''LMAXFOCKAE'''= 6 is required.		should test whether '''LMAXFOCKAE'''= 6 is required.

			More details on shape restoration are explained in M. Shishkin and G. Kresse, Phys. Rev. B 74, 035101 (2006) and M. Unzog ,A. Tal, and G. Kresse, Phys. Rev. B106,155133(2022)

	== Usefull Settings ==		== Usefull Settings ==

Huebsch at 10:22, 19 July 2022

2022-07-19T10:22:05Z

← Older revision		Revision as of 10:22, 19 July 2022
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	{{sc\|NMAXFOCKAE\|Examples\|Examples that use this tag}}		{{sc\|NMAXFOCKAE\|Examples\|Examples that use this tag}}
	----		----
	[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]][[Category:Many-~~Body Perturbation Theory~~]][[Category:GW]]		[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]][[Category:Many-body perturbation theory]][[Category:GW]]

Ftran at 12:45, 18 May 2022

2022-05-18T12:45:09Z

← Older revision		Revision as of 12:45, 18 May 2022
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	is usually treated on spherical grids centered at each atom		is usually treated on spherical grids centered at each atom
	(one-center terms inside the PAW spheres, see [[PAW method]] and more detailed description for {{TAG\|LMAXFOCK}}). To describe long range electrostatic effects, the ''moments'' of the differences of the all-electron and pseudo charge density		(one-center terms inside the PAW spheres, see [[Projector-augmented-wave_formalism\|PAW method]] and more detailed description for {{TAG\|LMAXFOCK}}). To describe long range electrostatic effects, the ''moments'' of the differences of the all-electron and pseudo charge density
	also need to be added on the plane wave grid (compensation density, see [[PAW method]]).		also need to be added on the plane wave grid (compensation density, see [[Projector-augmented-wave_formalism\|PAW method]]).
	These compensation charges exactly restore the moments of the all-electron density on the plane wave		These compensation charges exactly restore the moments of the all-electron density on the plane wave
	grid. For the Fock exchange the maximum ''L'' quantum number up to which		grid. For the Fock exchange the maximum ''L'' quantum number up to which

Karsai: /* Related Tags and Sections */

2022-04-08T14:33:53Z

Related Tags and Sections

← Older revision		Revision as of 14:33, 8 April 2022
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	* '''NMAXFOCKAE'''=2, to select the very accurate augmentation on the plane wave grid. Please check whether the VASP default setting for '''LMAXFOCKAE''' suffices (OUTCAR file). Use this setting only with care (noise).		* '''NMAXFOCKAE'''=2, to select the very accurate augmentation on the plane wave grid. Please check whether the VASP default setting for '''LMAXFOCKAE''' suffices (OUTCAR file). Use this setting only with care (noise).

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|LMAXFOCK}}, {{TAG\|QMAXFOCKAE}}, {{TAG\|LFOCKAEDFT}}		{{TAG\|LMAXFOCK}}, {{TAG\|QMAXFOCKAE}}, {{TAG\|LFOCKAEDFT}}

	{{sc\|NMAXFOCKAE\|Examples\|Examples that use this tag}}		{{sc\|NMAXFOCKAE\|Examples\|Examples that use this tag}}
	----		----
			[[Category:INCAR tag]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]][[Category:Many-Body Perturbation Theory]][[Category:GW]]
	[[Category:INCAR]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]][[Category:Many-Body Perturbation Theory]][[Category:GW]]

Ftran at 11:31, 8 April 2022

2022-04-08T11:31:25Z

← Older revision		Revision as of 11:31, 8 April 2022
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	----		----

	[[Category:INCAR]][[Category:Exchange-correlation functionals]][[Category:~~Hybrids~~]][[Category:Many-Body Perturbation Theory]][[Category:GW]]		[[Category:INCAR]][[Category:Exchange-correlation functionals]][[Category:Hybrid_functionals]][[Category:Many-Body Perturbation Theory]][[Category:GW]]

Ftran at 07:50, 6 April 2022

2022-04-06T07:50:24Z

← Older revision		Revision as of 07:50, 6 April 2022
Line 73:		Line 73:
	----		----

	[[Category:INCAR]][[Category:~~XC Functionals~~]][[Category:Hybrids]][[Category:Many-Body Perturbation Theory]][[Category:GW]]		[[Category:INCAR]][[Category:Exchange-correlation functionals]][[Category:Hybrids]][[Category:Many-Body Perturbation Theory]][[Category:GW]]

← Older revision		Revision as of 12:17, 29 March 2023
Line 37:		Line 37:
	To achieve the improved treatment on the plane wave grid, <math> Q_{\alpha\beta}({\mathbf r}) </math> is Fourier transformed to reciprocal space <math> Q_{\alpha\beta}(q) </math> and then expanded		To achieve the improved treatment on the plane wave grid, <math> Q_{\alpha\beta}({\mathbf r}) </math> is Fourier transformed to reciprocal space <math> Q_{\alpha\beta}(q) </math> and then expanded
	in a set of orthogonal functions localized at each atomic site. These augmentation charges		in a set of orthogonal functions localized at each atomic site. These augmentation charges
	are then added to the pseudo charge densities on the plane wave grid. Shape restoration is only accurate up to a certain plane wave cutoff, typically about 150 eV for '''NMAXFOCKAE''' =1, and 400 eV for '''NMAXFOCKAE''' = 2. ~~Experiences~~ shows, that '''NMAXFOCKAE''' =1 is sufficient to predict very accurate energy differences, and quite accurate quasiparticle energies.		are then added to the pseudo charge densities on the plane wave grid. Shape restoration is only accurate up to a certain plane wave cutoff, typically about 150 eV for '''NMAXFOCKAE''' =1, and 400 eV for '''NMAXFOCKAE''' = 2. Experience shows that '''NMAXFOCKAE''' =1 is sufficient to predict very accurate energy differences and quite accurate quasiparticle energies.


	For '''LMAXFOCKAE'''=-1 (the default for DFT and Hartree-Fock calculations), only the moments of the all-electron charge densities are restored on the plane wave grid. This is the default for Hartree-Fock calculations, and the setting is very precise since for Hartree-Fock the one-center terms are implemented in radial grids
	~~as for DFT.~~

	If '''LMAXFOCKAE''' is set to values larger than -1 (and '''NMAXFOCKAE'''=1), not only the moments of the all-electron charge density are restored on the plane wave grid, but also the all-electron charge density is restored up to a typical plane wave energy of ~~140~~ eV (controlled by {{TAG\|QMAXFOCKAE}}). This setting yields very accurate results for post DFT methods (MP2, RPA, GW, etc.) for most sp bonded materials. '''LMAXFOCKAE''' is used to specify the maximum spherical (''L'') quantum number up		For '''LMAXFOCKAE'''=-1 (the default for DFT and Hartree-Fock calculations), only the moments of the all-electron charge densities are restored on the plane wave grid. This is the default for Hartree-Fock calculations, and the setting is very precise since for Hartree-Fock the one-center terms are implemented in radial grids as for DFT.

			If '''LMAXFOCKAE''' is set to values larger than -1 (and '''NMAXFOCKAE'''=1), not only the moments of the all-electron charge density are restored on the plane wave grid, but also the all-electron charge density is restored up to a typical plane wave energy of 150 eV (controlled by {{TAG\|QMAXFOCKAE}}). This setting yields very accurate results for post DFT methods (MP2, RPA, GW, etc.) for most sp bonded materials. '''LMAXFOCKAE''' is used to specify the maximum spherical (''L'') quantum number up
	to which this more accurate treatment is used. The default is '''LMAXFOCKAE'''=4 for post DFT methods.		to which this more accurate treatment is used. The default is '''LMAXFOCKAE'''=4 for post DFT methods.
	If no accurate augmentation is desired by the user, simply set '''LMAXFOCKAE'''=-1 in the INCAR file.		If no accurate augmentation is desired by the user, simply set '''LMAXFOCKAE'''=-1 in the INCAR file.

	If '''LMAXFOCKAE''' is set to values larger than -1 and '''NMAXFOCKAE'''=2, the charge density is restored accurately on the plane wave grid up to a typical plane wave energy of ~~380~~ eV. As before, '''LMAXFOCKAE''' can be used to specify the maximum spherical (''L'') quantum number up		If '''LMAXFOCKAE''' is set to values larger than -1 and '''NMAXFOCKAE'''=2, the charge density is restored accurately on the plane wave grid up to a typical plane wave energy of 400 eV. As before, '''LMAXFOCKAE''' can be used to specify the maximum spherical (''L'') quantum number up
	to which this more accurate treatment is used. '''NMAXFOCKAE'''=2 yields very accurate results for		to which this more accurate treatment is used. '''NMAXFOCKAE'''=2 yields very accurate results for
	post DFT methods (MP2, RPA, GW) even for difficult 3d elements. For RPA and MP2 total energy calculations, differences between '''NMAXFOCKAE'''=1 and '''NMAXFOCKAE'''=2 are usually tiny for total energy differences. Since the absolute correlation energies might change, it is, however, vital to use the same setting for		post DFT methods (MP2, RPA, GW) even for difficult 3d elements. For RPA and MP2 total energy calculations, differences between '''NMAXFOCKAE'''=1 and '''NMAXFOCKAE'''=2 are usually tiny for total energy differences. Since the absolute correlation energies might change, it is, however, vital to use the same setting for
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	* '''LMAXFOCKAE'''=-1, to switch off the accurate augmentation altogether (reduces noise in correlation energies).		* '''LMAXFOCKAE'''=-1, to switch off the accurate augmentation altogether (reduces noise in correlation energies).
	* '''LMAXFOCKAE'''=4 (or larger) to force an accurate treatment for the charge augmentation on the plane wave grid (can be selected even in Hartree-Fock type calculations, but causes some additional noise).		* '''LMAXFOCKAE'''=4 (or larger) to force an accurate treatment for the charge augmentation on the plane wave grid (can be selected even in Hartree-Fock type calculations, but causes some additional noise).
	* '''NMAXFOCKAE'''=2, to select the very accurate augmentation on the plane wave grid. Please check whether the VASP default setting for '''LMAXFOCKAE''' suffices (OUTCAR file). Use this setting only with care ~~(noise)~~.		* '''NMAXFOCKAE'''=2, to select the very accurate augmentation on the plane wave grid. Please check whether the VASP default setting for '''LMAXFOCKAE''' suffices (OUTCAR file). Use this setting only with care, as it can result in very noisy data for coarse FFT grids.

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