PREC - Revision history

Ftran at 08:32, 14 October 2025

2025-10-14T08:32:09Z

← Older revision		Revision as of 08:32, 14 October 2025
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	{{TAG\|PREC}} sets default values for the energy cutoff {{TAG\|ENCUT}}, the FFT grids ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) and ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}), and the accuracy of the projectors in real space {{TAG\|ROPT}} (used only when {{TAG\|LREAL}}=.TRUE.). Details are given below in the table.		{{TAG\|PREC}} sets default values for the energy cutoff {{TAG\|ENCUT}}, the FFT grids ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) and ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}), and the accuracy of the projectors in real space {{TAG\|ROPT}} (used only when {{TAG\|LREAL}}=.TRUE.). Details are given below in the table.

	We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps.		We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps. More details can be found at [[Energy_cut_off_and_FFT_mesh\|Energy cutoff and FFT mesh]].
	{{NB\|important\|		{{NB\|important\|
	*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.		*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.
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	{{TAG\|ADDGRID}},		{{TAG\|ADDGRID}},
	{{TAG\|PRECFOCK}},		{{TAG\|PRECFOCK}},
	[[Energy_cut_off_and_FFT_mesh]],		[[Energy_cut_off_and_FFT_mesh\|Energy cutoff and FFT mesh]],
	[[Wrap-around_errors]]		[[Wrap-around_errors\|Wrap-around errors]]

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

	[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]		[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]

Ftran at 08:23, 14 October 2025

2025-10-14T08:23:39Z

← Older revision		Revision as of 08:23, 14 October 2025
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	{{TAG\|LREAL}},		{{TAG\|LREAL}},
	{{TAG\|ADDGRID}},		{{TAG\|ADDGRID}},
	{{TAG\|PRECFOCK}}		{{TAG\|PRECFOCK}},
			[[Energy_cut_off_and_FFT_mesh]],
			[[Wrap-around_errors]]

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

	[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]		[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]

Ftran at 08:19, 14 October 2025

2025-10-14T08:19:01Z

← Older revision		Revision as of 08:19, 14 October 2025
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	*{{TAG\|PREC}}=Single uses the same grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) as {{TAG\|PREC}}=Normal in VASP.5, but the same grid as {{TAG\|PREC}}=Accurate in VASP.6. However, the double grid technique is not used, i.e., ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}})=({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). This is convenient if one needs to cut down on storage demands or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high-frequency oscillations caused by the double-grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high-frequency wiggles of the charge density in the vacuum region are undesirable.		*{{TAG\|PREC}}=Single uses the same grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) as {{TAG\|PREC}}=Normal in VASP.5, but the same grid as {{TAG\|PREC}}=Accurate in VASP.6. However, the double grid technique is not used, i.e., ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}})=({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). This is convenient if one needs to cut down on storage demands or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high-frequency oscillations caused by the double-grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high-frequency wiggles of the charge density in the vacuum region are undesirable.

	*{{TAG\|PREC}}=Medium and {{TAG\|PREC}}=Normal should usually be sufficiently accurate and lead to errors of less than 1 meV/atom.

	*{{TAG\|PREC}}=High should guarantee that the absolute energies are converged to a few meV and the stress tensor converged within a few kBar.		*{{TAG\|PREC}}=High should guarantee that the absolute energies are converged to a few meV and the stress tensor converged within a few kBar.

Ftran at 08:06, 14 October 2025

2025-10-14T08:06:51Z

← Older revision		Revision as of 08:06, 14 October 2025
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	We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps.		We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps.
			{{NB\|important\|
			*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.
			*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.
			*Setting {{TAG\|ENAUG}} has an effect only if {{TAG\|PREC}} is set to one of the deprecated settings (Low, Medium or High); otherwise, it is ignored.}}
	{{NB\|mind\|		{{NB\|mind\|
	*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.		*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.
	*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}		*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}
	{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium, High and Low are no longer recommended and are available only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}		{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium, High and Low are no longer recommended and are available only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}
	~~{{NB\|important\|~~
	*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.
	*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.
	*Setting {{TAG\|ENAUG}} has an effect only if {{TAG\|PREC}} is set to one of the deprecated settings (Low, Medium or High); otherwise, it is ignored.}}

	== Default values set by {{TAG\|PREC}} ==		== Default values set by {{TAG\|PREC}} ==

Ftran at 07:57, 14 October 2025

2025-10-14T07:57:27Z

← Older revision		Revision as of 07:57, 14 October 2025
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	*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.		*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.
	*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}		*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}
	{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium and ~~{{TAG\|PREC}}{{=}}High~~ are no longer recommended and are available ~~(as well as {{TAG\|PREC}}{{=}}Low)~~ only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}		{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium, High and Low are no longer recommended and are available only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}
	{{NB\|important\|		{{NB\|important\|
	*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.		*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.

Huebsch at 11:57, 17 October 2024

2024-10-17T11:57:25Z

← Older revision		Revision as of 11:57, 17 October 2024
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	{{sc\|PREC\|Examples\|Examples that use this tag}}		{{sc\|PREC\|Examples\|Examples that use this tag}}
	~~----~~

	[[Category:INCAR tag]][[Category:~~Electronic minimization~~]][[Category:Memory]]		[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]

Ftran at 10:00, 31 October 2023

2023-10-31T10:00:29Z

Show changes

Schlipf at 12:31, 14 June 2023

2023-06-14T12:31:05Z

← Older revision		Revision as of 12:31, 14 June 2023
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	\| Single (VASP.6) \|\|align="center"\|max({{TAG\|ENMAX}}) \|\| 2 ×G<sub>cut</sub> \|\|align="center"\|{{TAG\|NGX}} \|\|-5×10<sup>-4</sup>		\| Single (VASP.6) \|\|align="center"\|max({{TAG\|ENMAX}}) \|\| 2 ×G<sub>cut</sub> \|\|align="center"\|{{TAG\|NGX}} \|\|-5×10<sup>-4</sup>
	\|-		\|-
	\|SingleN (VASP.6 ~~development~~)		\|SingleN (VASP.6)
	\|align="center"\|max({{TAG\|ENMAX}})		\|align="center"\|max({{TAG\|ENMAX}})
	\|3/2×G<sub>cut</sub>		\|3/2×G<sub>cut</sub>

Huebsch at 09:04, 25 May 2022

2022-05-25T09:04:04Z

← Older revision		Revision as of 09:04, 25 May 2022
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	----		----

	[[Category:INCAR tag]][[Category:Electronic minimization]]		[[Category:INCAR tag]][[Category:Electronic minimization]][[Category:Memory]]

Huebsch at 15:28, 6 April 2022

2022-04-06T15:28:06Z

← Older revision		Revision as of 15:28, 6 April 2022
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	Description: {{TAG\|PREC}} specifies the "precision"-mode.		Description: {{TAG\|PREC}} specifies the "precision"-mode.
	----		----
	We recommend ~~to use~~ {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate.		We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate.
	The settings {{TAG\|PREC}}=Medium and {{TAG\|PREC}}=High (available already in VASP.4.4)		The settings {{TAG\|PREC}}=Medium and {{TAG\|PREC}}=High (available already in VASP.4.4)
	are no longer recommended. {{TAG\|PREC}}=Normal can be used for most		are no longer recommended. {{TAG\|PREC}}=Normal can be used for most
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	this really helps).		this really helps).

	The use of {{TAG\|PREC}}=High is no longer ~~recommend~~ (and is only available for compatibility). Essentially {{TAG\|PREC}}=High only increases the energy cutoff		The use of {{TAG\|PREC}}=High is no longer recommended (and is only available for compatibility). Essentially {{TAG\|PREC}}=High only increases the energy cutoff
	by 30 %. The same effect can be achieved by just manually increasing {{TAG\|ENCUT}}		by 30 %. The same effect can be achieved by just manually increasing {{TAG\|ENCUT}}
	in the INCAR file. If, additionally, very accurate forces are required, {{TAG\|PREC}}=Accurate can be used in combination with an increased energy cutoff.		in the INCAR file. If, additionally, very accurate forces are required, {{TAG\|PREC}}=Accurate can be used in combination with an increased energy cutoff.

	'''Mind''': we recommend ~~to specify~~ the energy cutoff ({{TAG\|ENCUT}}) always manually in the {{FILE\|INCAR}} file, to avoid incompatibilities between calculations.		'''Mind''': we recommend specifying the energy cutoff ({{TAG\|ENCUT}}) always manually in the {{FILE\|INCAR}} file, to avoid incompatibilities between calculations.
	----		----
	The {{TAG\|PREC}} parameter sets the defaults for four sets of parameters ({{TAG\|ENCUT}}; {{TAG\|NGX}}, {{TAG\|NGY}}, {{TAG\|NGZ}}; {{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}, and {{TAG\|ROPT}}):		The {{TAG\|PREC}} parameter sets the defaults for four sets of parameters ({{TAG\|ENCUT}}; {{TAG\|NGX}}, {{TAG\|NGY}}, {{TAG\|NGZ}}; {{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}, and {{TAG\|ROPT}}):
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	:In addition, the {{TAG\|PREC}} tag determines the spacing for the grids representing the augmentation charges, charge densities and potentials ({{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}). For {{TAG\|PREC}}=Accurate and {{TAG\|PREC}}=Normal, the support grid contains twice as many points in each direction as the grids for the orbitals ({{TAG\|NGXF}}=2×{{TAG\|NGX}}, {{TAG\|NGYF}}=2×{{TAG\|NGY}}, {{TAG\|NGZF}}=2×{{TAG\|NGZ}}). In all other cases, {{TAG\|NGXF}}, {{TAG\|NGYF}}, and {{TAG\|NGZF}} are determined by some heuristic formula from {{TAG\|ENAUG}} (these settings should be avoided).		:In addition, the {{TAG\|PREC}} tag determines the spacing for the grids representing the augmentation charges, charge densities and potentials ({{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}). For {{TAG\|PREC}}=Accurate and {{TAG\|PREC}}=Normal, the support grid contains twice as many points in each direction as the grids for the orbitals ({{TAG\|NGXF}}=2×{{TAG\|NGX}}, {{TAG\|NGYF}}=2×{{TAG\|NGY}}, {{TAG\|NGZF}}=2×{{TAG\|NGZ}}). In all other cases, {{TAG\|NGXF}}, {{TAG\|NGYF}}, and {{TAG\|NGZF}} are determined by some heuristic formula from {{TAG\|ENAUG}} (these settings should be avoided).

	:{{TAG\|PREC}}=Single is uses the same FFT grids as {{TAG\|PREC}}=Normal in VASP.5 and the same FFT grids as {{TAG\|PREC}}=Accurate in VASP.6. The double grid technique is not used. This is convenient, if one needs to cut down on storage demands, or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high frequency oscillations caused the double grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high frequency wiggles of the charge density in the vacuum region are undesirable.		:{{TAG\|PREC}}=Single uses the same FFT grids as {{TAG\|PREC}}=Normal in VASP.5 and the same FFT grids as {{TAG\|PREC}}=Accurate in VASP.6. The double grid technique is not used. This is convenient, if one needs to cut down on storage demands, or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high-frequency oscillations caused by the double-grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high-frequency wiggles of the charge density in the vacuum region are undesirable.

	*Real space projectors ({{TAG\|ROPT}}):		*Real space projectors ({{TAG\|ROPT}}):
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	\|}		\|}

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|NGX}},		{{TAG\|NGX}},
	{{TAG\|NGY}},		{{TAG\|NGY}},
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	----		----

	[[Category:INCAR]][[Category:Electronic ~~Minimization]][[Category:Electronic Minimization Methods~~]]		[[Category:INCAR tag]][[Category:Electronic minimization]]

← Older revision		Revision as of 08:32, 14 October 2025
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	{{TAG\|PREC}} sets default values for the energy cutoff {{TAG\|ENCUT}}, the FFT grids ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) and ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}), and the accuracy of the projectors in real space {{TAG\|ROPT}} (used only when {{TAG\|LREAL}}=.TRUE.). Details are given below in the table.		{{TAG\|PREC}} sets default values for the energy cutoff {{TAG\|ENCUT}}, the FFT grids ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) and ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}), and the accuracy of the projectors in real space {{TAG\|ROPT}} (used only when {{TAG\|LREAL}}=.TRUE.). Details are given below in the table.

	We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps.		We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps. More details can be found at [[Energy_cut_off_and_FFT_mesh\|Energy cutoff and FFT mesh]].
	{{NB\|important\|		{{NB\|important\|
	*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.		*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.
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	{{TAG\|ADDGRID}},		{{TAG\|ADDGRID}},
	{{TAG\|PRECFOCK}},		{{TAG\|PRECFOCK}},
	[[Energy_cut_off_and_FFT_mesh]],		[[Energy_cut_off_and_FFT_mesh\|Energy cutoff and FFT mesh]],
	[[Wrap-around_errors]]		[[Wrap-around_errors\|Wrap-around errors]]

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

	[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]		[[Category:INCAR tag]][[Category:Projector-augmented-wave method]][[Category:Memory]]

← Older revision		Revision as of 08:19, 14 October 2025
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	*{{TAG\|PREC}}=Single uses the same grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) as {{TAG\|PREC}}=Normal in VASP.5, but the same grid as {{TAG\|PREC}}=Accurate in VASP.6. However, the double grid technique is not used, i.e., ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}})=({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). This is convenient if one needs to cut down on storage demands or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high-frequency oscillations caused by the double-grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high-frequency wiggles of the charge density in the vacuum region are undesirable.		*{{TAG\|PREC}}=Single uses the same grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) as {{TAG\|PREC}}=Normal in VASP.5, but the same grid as {{TAG\|PREC}}=Accurate in VASP.6. However, the double grid technique is not used, i.e., ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}})=({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). This is convenient if one needs to cut down on storage demands or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high-frequency oscillations caused by the double-grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high-frequency wiggles of the charge density in the vacuum region are undesirable.

	*{{TAG\|PREC}}=Medium and {{TAG\|PREC}}=Normal should usually be sufficiently accurate and lead to errors of less than 1 meV/atom.

	*{{TAG\|PREC}}=High should guarantee that the absolute energies are converged to a few meV and the stress tensor converged within a few kBar.		*{{TAG\|PREC}}=High should guarantee that the absolute energies are converged to a few meV and the stress tensor converged within a few kBar.

← Older revision		Revision as of 08:06, 14 October 2025
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	We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps.		We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate. {{TAG\|PREC}}=Normal can be used for most routine calculations. {{TAG\|PREC}}=Accurate leads to a denser grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}). Thus, it reduces egg-box effects and strictly avoids any [[Wrap-around errors\|aliasing/wrap-around errors]]. {{TAG\|PREC}}=Normal and {{TAG\|PREC}}=Accurate use an augmentation fine grid ({{TAG\|NGXF}},{{TAG\|NGYF}},{{TAG\|NGZF}}) that is twice larger than the grid ({{TAG\|NGX}},{{TAG\|NGY}},{{TAG\|NGZ}}) used for the representation of the pseudo-orbitals. {{TAG\|PREC}}=Accurate increases the memory requirements somewhat, but it should be used (in combination with an increased value for {{TAG\|ENCUT}}) when a very good accuracy is required, e.g., for accurate forces, for phonons and stress tensor or in general when second derivatives are computed. The accuracy of forces can also be sometimes further improved by specifying {{TAG\|ADDGRID}}=.TRUE., however, reports from users are somewhat contradictory about whether this really helps.
			{{NB\|important\|
			*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.
			*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.
			*Setting {{TAG\|ENAUG}} has an effect only if {{TAG\|PREC}} is set to one of the deprecated settings (Low, Medium or High); otherwise, it is ignored.}}
	{{NB\|mind\|		{{NB\|mind\|
	*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.		*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.
	*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}		*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}
	{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium, High and Low are no longer recommended and are available only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}		{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium, High and Low are no longer recommended and are available only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}
	~~{{NB\|important\|~~
	*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.
	*We strongly recommend specifying the energy cutoff {{TAG\|ENCUT}} always manually in the {{FILE\|INCAR}} file to ensure the same accuracy between calculations. Otherwise, the default {{TAG\|ENCUT}} may differ among the different calculations (e.g., for the calculation of the cohesive energy), with the consequence that the total energies, for instance, can not be compared.
	*Setting {{TAG\|ENAUG}} has an effect only if {{TAG\|PREC}} is set to one of the deprecated settings (Low, Medium or High); otherwise, it is ignored.}}

	== Default values set by {{TAG\|PREC}} ==		== Default values set by {{TAG\|PREC}} ==

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	*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.		*The value of a parameter set by {{TAG\|PREC}} (e.g., {{TAG\|ENCUT}}) can be overridden by specifying explicitly the value of that parameter in the {{FILE\|INCAR}} file.
	*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}		*{{TAG\|PREC}}{{=}}Normal and {{TAG\|PREC}}{{=}}Accurate are only available in VASP.4.5 and newer versions. The setting {{TAG\|PREC}}{{=}}Single is only available as of VASP.5.1, and has been updated in VASP.6.}}
	{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium and ~~{{TAG\|PREC}}{{=}}High~~ are no longer recommended and are available ~~(as well as {{TAG\|PREC}}{{=}}Low)~~ only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}		{{NB\|deprecated\|The old settings {{TAG\|PREC}}{{=}}Medium, High and Low are no longer recommended and are available only for backward compatibility. Essentially, {{TAG\|PREC}}{{=}}High only increases the energy cutoff by 30 %, which can also be achieved by just manually increasing {{TAG\|ENCUT}}.}}
	{{NB\|important\|		{{NB\|important\|
	*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.		*Setting {{TAG\|PREC}}{{=}}Accurate does not necessarily mean that the results are converged. The convergence of the results with respect to the energy cutoff {{TAG\|ENCUT}} has to be checked separately.

← Older revision		Revision as of 15:28, 6 April 2022
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	Description: {{TAG\|PREC}} specifies the "precision"-mode.		Description: {{TAG\|PREC}} specifies the "precision"-mode.
	----		----
	We recommend ~~to use~~ {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate.		We recommend using {{TAG\|PREC}}=Normal or {{TAG\|PREC}}=Accurate.
	The settings {{TAG\|PREC}}=Medium and {{TAG\|PREC}}=High (available already in VASP.4.4)		The settings {{TAG\|PREC}}=Medium and {{TAG\|PREC}}=High (available already in VASP.4.4)
	are no longer recommended. {{TAG\|PREC}}=Normal can be used for most		are no longer recommended. {{TAG\|PREC}}=Normal can be used for most
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	this really helps).		this really helps).

	The use of {{TAG\|PREC}}=High is no longer ~~recommend~~ (and is only available for compatibility). Essentially {{TAG\|PREC}}=High only increases the energy cutoff		The use of {{TAG\|PREC}}=High is no longer recommended (and is only available for compatibility). Essentially {{TAG\|PREC}}=High only increases the energy cutoff
	by 30 %. The same effect can be achieved by just manually increasing {{TAG\|ENCUT}}		by 30 %. The same effect can be achieved by just manually increasing {{TAG\|ENCUT}}
	in the INCAR file. If, additionally, very accurate forces are required, {{TAG\|PREC}}=Accurate can be used in combination with an increased energy cutoff.		in the INCAR file. If, additionally, very accurate forces are required, {{TAG\|PREC}}=Accurate can be used in combination with an increased energy cutoff.

	'''Mind''': we recommend ~~to specify~~ the energy cutoff ({{TAG\|ENCUT}}) always manually in the {{FILE\|INCAR}} file, to avoid incompatibilities between calculations.		'''Mind''': we recommend specifying the energy cutoff ({{TAG\|ENCUT}}) always manually in the {{FILE\|INCAR}} file, to avoid incompatibilities between calculations.
	----		----
	The {{TAG\|PREC}} parameter sets the defaults for four sets of parameters ({{TAG\|ENCUT}}; {{TAG\|NGX}}, {{TAG\|NGY}}, {{TAG\|NGZ}}; {{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}, and {{TAG\|ROPT}}):		The {{TAG\|PREC}} parameter sets the defaults for four sets of parameters ({{TAG\|ENCUT}}; {{TAG\|NGX}}, {{TAG\|NGY}}, {{TAG\|NGZ}}; {{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}, and {{TAG\|ROPT}}):
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	:In addition, the {{TAG\|PREC}} tag determines the spacing for the grids representing the augmentation charges, charge densities and potentials ({{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}). For {{TAG\|PREC}}=Accurate and {{TAG\|PREC}}=Normal, the support grid contains twice as many points in each direction as the grids for the orbitals ({{TAG\|NGXF}}=2×{{TAG\|NGX}}, {{TAG\|NGYF}}=2×{{TAG\|NGY}}, {{TAG\|NGZF}}=2×{{TAG\|NGZ}}). In all other cases, {{TAG\|NGXF}}, {{TAG\|NGYF}}, and {{TAG\|NGZF}} are determined by some heuristic formula from {{TAG\|ENAUG}} (these settings should be avoided).		:In addition, the {{TAG\|PREC}} tag determines the spacing for the grids representing the augmentation charges, charge densities and potentials ({{TAG\|NGXF}}, {{TAG\|NGYF}}, {{TAG\|NGZF}}). For {{TAG\|PREC}}=Accurate and {{TAG\|PREC}}=Normal, the support grid contains twice as many points in each direction as the grids for the orbitals ({{TAG\|NGXF}}=2×{{TAG\|NGX}}, {{TAG\|NGYF}}=2×{{TAG\|NGY}}, {{TAG\|NGZF}}=2×{{TAG\|NGZ}}). In all other cases, {{TAG\|NGXF}}, {{TAG\|NGYF}}, and {{TAG\|NGZF}} are determined by some heuristic formula from {{TAG\|ENAUG}} (these settings should be avoided).

	:{{TAG\|PREC}}=Single is uses the same FFT grids as {{TAG\|PREC}}=Normal in VASP.5 and the same FFT grids as {{TAG\|PREC}}=Accurate in VASP.6. The double grid technique is not used. This is convenient, if one needs to cut down on storage demands, or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high frequency oscillations caused the double grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high frequency wiggles of the charge density in the vacuum region are undesirable.		:{{TAG\|PREC}}=Single uses the same FFT grids as {{TAG\|PREC}}=Normal in VASP.5 and the same FFT grids as {{TAG\|PREC}}=Accurate in VASP.6. The double grid technique is not used. This is convenient, if one needs to cut down on storage demands, or if one wants to reduce the size of the files {{FILE\|CHG}} and {{FILE\|CHGCAR}}. Furthermore, {{TAG\|PREC}}=Single avoids high-frequency oscillations caused by the double-grid technique and the resulting Fourier interpolation. It is often expedient for scanning tunneling simulations or other calculations where high-frequency wiggles of the charge density in the vacuum region are undesirable.

	*Real space projectors ({{TAG\|ROPT}}):		*Real space projectors ({{TAG\|ROPT}}):
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	\|}		\|}

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|NGX}},		{{TAG\|NGX}},
	{{TAG\|NGY}},		{{TAG\|NGY}},
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	----		----

	[[Category:INCAR]][[Category:Electronic ~~Minimization]][[Category:Electronic Minimization Methods~~]]		[[Category:INCAR tag]][[Category:Electronic minimization]]