LEPSILON - Revision history

Huebsch at 09:54, 12 March 2026

2026-03-12T09:54:54Z

← Older revision		Revision as of 09:54, 12 March 2026
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	[[Electric field response from density-functional-perturbation theory]]		[[Electric field response from density-functional-perturbation theory]]

	{{sc\|LEPSILON\|~~Examples~~\|~~Examples~~ that use this tag}}		{{sc\|LEPSILON\|HowTo\|Workflows that use this tag}}

	== References ==		== References ==

	[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric properties]]		[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric properties]]

Csheldon: /* Related tags and articles */

2026-01-22T14:04:15Z

Csheldon at 14:01, 22 January 2026

2026-01-22T14:01:18Z

← Older revision		Revision as of 14:01, 22 January 2026
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	Description: {{TAG\|LEPSILON}}=.TRUE. determines the static dielectric matrix, ion-clamped piezoelectric tensor, and the Born effective charges using density functional perturbation theory.		Description: {{TAG\|LEPSILON}}=.TRUE. determines the static dielectric matrix, ion-clamped piezoelectric tensor, and the Born effective charges using density functional perturbation theory.
	----		----
	Determines the static ion-clamped dielectric matrix using density functional perturbation		Determines the static ion-clamped dielectric matrix using [[Electric field response from density-functional-perturbation theory \| density functional perturbation theory]] (DFPT). The dielectric matrix is calculated with and without local field effects. Usually, local field effects are determined on the Hartree level, i.e. including changes of the Hartree potential.
	theory. The dielectric matrix is calculated with and without local field effects. Usually, local field effects are determined on the Hartree level, i.e. including changes of the Hartree potential.
	To include microscopic changes of the exchange-correlation potential		To include microscopic changes of the exchange-correlation potential
	the tag {{TAG\|LRPA}}=.FALSE. must be set. The method is explained in detail in paper by Gajdoš ''et al.'' {{Cite\|gajdos:hummer:2006}} and closely follows the original work of Baroni and Resta {{Cite\|baroni:resta:1986}}.		the tag {{TAG\|LRPA}}=.FALSE. must be set. The method is explained in detail in paper by Gajdoš ''et al.'' {{Cite\|gajdos:hummer:2006}} and closely follows the original work of Baroni and Resta {{Cite\|baroni:resta:1986}}.

Csheldon at 15:38, 21 March 2025

2025-03-21T15:38:18Z

Miranda.henrique at 11:23, 8 February 2024

2024-02-08T11:23:23Z

← Older revision		Revision as of 11:23, 8 February 2024
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	----		----

	[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric ~~properties]][[Category:Static dielectric~~ properties]]		[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric properties]]

Huebsch at 09:21, 24 October 2023

2023-10-24T09:21:39Z

← Older revision		Revision as of 09:21, 24 October 2023
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	Note that the routine also parses and uses the value supplied in the {{TAG\|LNABLA}} tag.		Note that the routine also parses and uses the value supplied in the {{TAG\|LNABLA}} tag.
	Furthermore, the routine calculates the Born effective charge tensor (dynamical charges) and electronic contribution to ~~the~~ the piezoelectric tensor ,		Furthermore, the routine calculates the Born effective charge tensor (dynamical charges) and electronic contribution to the piezoelectric tensor ,
	and prints them after		and prints them after
	BORN EFFECTIVE CHARGES (in e, cummulative output)		BORN EFFECTIVE CHARGES (in e, cummulative output)
	and		and
	PIEZOELECTRIC TENSOR for field in x, y, z (C/m^2)		PIEZOELECTRIC TENSOR for field in x, y, z (C/m^2)
	if {{TAG\|LRPA}}=.FALSE. is set (the calculated tensors are not sensible in the random phase approximation {{TAG\|LRPA}}=.TRUE.).		if {{TAG\|LRPA}}=.FALSE. is set (the calculated tensors are not sensible in the random phase approximation {{TAG\|LRPA}}=.TRUE.). Regarding the piezoelectric tensor, mind the [[ISIF\|definition/sign convention of the stress tensor]].

Karsai: /* References */

2022-07-19T07:46:58Z

References

← Older revision		Revision as of 07:46, 19 July 2022
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	----		----

	[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric ~~Properties~~]][[Category:Static dielectric properties]]		[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric properties]][[Category:Static dielectric properties]]

Karsai: /* References */

2022-04-08T14:30:54Z

References

← Older revision		Revision as of 14:30, 8 April 2022
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	</references>		</references>
	----		----
	~~[[The_VASP_Manual\|Contents]]~~

	[[Category:INCAR]][[Category:Linear response]][[Category:Dielectric Properties]][[Category:Static dielectric properties]]		[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric Properties]][[Category:Static dielectric properties]]

Karsai: /* Related Tags and Sections */

2022-04-08T14:30:45Z

Related Tags and Sections

← Older revision		Revision as of 14:30, 8 April 2022
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	Density functional perturbation theory {{TAG\|LEPSILON}}=.TRUE. does not require to increase {{TAG\|NBANDS}} and is, in fact, much slower if {{TAG\|NBANDS}} is increased, whereas the summation over emtpy conduction band states requires a large number of such states.		Density functional perturbation theory {{TAG\|LEPSILON}}=.TRUE. does not require to increase {{TAG\|NBANDS}} and is, in fact, much slower if {{TAG\|NBANDS}} is increased, whereas the summation over emtpy conduction band states requires a large number of such states.

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|LOPTICS}},		{{TAG\|LOPTICS}},
	{{TAG\|LRPA}},		{{TAG\|LRPA}},

Karsai: /* References */

2019-03-08T13:38:11Z

References

← Older revision		Revision as of 13:38, 8 March 2019
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	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR]][[Category:Static dielectric properties]]		[[Category:INCAR]][[Category:Linear response]][[Category:Dielectric Properties]][[Category:Static dielectric properties]]

← Older revision		Revision as of 14:04, 22 January 2026
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	{{TAG\|LRPA}},		{{TAG\|LRPA}},
	{{TAG\|LCALCEPS}},		{{TAG\|LCALCEPS}},
	{{TAG\|IBRION}}		{{TAG\|IBRION}},
			[[Electric field response from density-functional-perturbation theory]]

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

← Older revision		Revision as of 15:38, 21 March 2025
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	{{TAGDEF\|LEPSILON\|.TRUE. {{!}} .FALSE.\|.FALSE.}}		{{TAGDEF\|LEPSILON\|.TRUE. {{!}} .FALSE.\|.FALSE.}}

	Description: {{TAG\|LEPSILON}}=.TRUE. determines the static dielectric matrix, ion-clamped piezoelectric tensor and the Born effective charges using density functional perturbation theory.		Description: {{TAG\|LEPSILON}}=.TRUE. determines the static dielectric matrix, ion-clamped piezoelectric tensor, and the Born effective charges using density functional perturbation theory.
	----		----
	Determines the static ion-clamped dielectric matrix using density functional perturbation		Determines the static ion-clamped dielectric matrix using density functional perturbation
	theory. The dielectric matrix is calculated with and without local field effects. Usually local field effects are determined on the Hartree level, i.e. including changes of the Hartree potential.		theory. The dielectric matrix is calculated with and without local field effects. Usually, local field effects are determined on the Hartree level, i.e. including changes of the Hartree potential.
	To include microscopic changes of the exchange correlation potential		To include microscopic changes of the exchange-correlation potential
	the tag {{TAG\|LRPA}}=.FALSE. must be set. The method is explained in detail in paper by Gajdoš ''et al.''~~,<ref name="~~gajdos:~~prb~~:~~06"/>~~ and closely follows the original work of Baroni and Resta~~.<ref name="~~baroni:~~prb~~:~~86"/>~~		the tag {{TAG\|LRPA}}=.FALSE. must be set. The method is explained in detail in paper by Gajdoš ''et al.'' {{Cite\|gajdos:hummer:2006}} and closely follows the original work of Baroni and Resta {{Cite\|baroni:resta:1986}}.
	A summation over empty conduction band states is not required, instead the usual expressions in perturbation theory ({{TAG\|LOPTICS}}=.TRUE.),		A summation over empty conduction band states is not required, instead the usual expressions in perturbation theory ({{TAG\|LOPTICS}}=.TRUE.),

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	RMM: 5 -0.13949E+01 0.28357E-04 -0.25757E-04 228 0.177E-01 0.126E-02		RMM: 5 -0.13949E+01 0.28357E-04 -0.25757E-04 228 0.177E-01 0.126E-02

	It is important to note that exact values for the dielectric matrix are obtained even if only valence band states are calculated. Hence this method does not require ~~to increase~~ the {{TAG\|NBANDS}} parameter. The final values for the static dielectric matrix can be found in the {{FILE\|OUTCAR}} file after the lines		It is important to note that exact values for the dielectric matrix are obtained even if only valence band states are calculated. Hence this method does not require increasing the {{TAG\|NBANDS}} parameter. The final values for the static dielectric matrix can be found in the {{FILE\|OUTCAR}} file after the lines
	MICROSCOPIC STATIC DIELECTRIC TENSOR (excluding local field effects)		MICROSCOPIC STATIC DIELECTRIC TENSOR (excluding local field effects)
	and		and
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	The values found after <tt>MACROSCOPIC STATIC DIELECTRIC TENSOR (excluding local field effects)</tt> should match exactly to the zero frequency values ω→0 determined by the method selected using {{TAG\|LOPTICS}}=.TRUE..		The values found after <tt>MACROSCOPIC STATIC DIELECTRIC TENSOR (excluding local field effects)</tt> should match exactly to the zero frequency values ω→0 determined by the method selected using {{TAG\|LOPTICS}}=.TRUE..
	This offers a convenient way to determine how many empty bands are required for		This offers a convenient way to determine how many empty bands are required for
	{{TAG\|LOPTICS}}=.TRUE.. Simply execute VASP using {{TAG\|LEPSILON}}=.TRUE. in order to determine the exact values for the dielectric constants. Next, switch to {{TAG\|LOPTICS}}=.TRUE. and increase the number of conduction bands until the same values are obtained as using density functional perturbation theory.		{{TAG\|LOPTICS}}=.TRUE.. Simply execute VASP using {{TAG\|LEPSILON}}=.TRUE. in order to determine the exact values for the dielectric constants. Next, switch to {{TAG\|LOPTICS}}=.TRUE. and increase the number of conduction bands until the same values are obtained using density functional perturbation theory.

	Note that the routine also parses and uses the value supplied in the {{TAG\|LNABLA}} tag.		Note that the routine also parses and uses the value supplied in the {{TAG\|LNABLA}} tag.
	Furthermore, the routine calculates the Born effective charge tensor (dynamical charges) and electronic contribution to the piezoelectric tensor ,		Furthermore, the routine calculates the Born effective charge tensor (dynamical charges) and electronic contribution to the piezoelectric tensor,
	and prints them after		and prints them after
	BORN EFFECTIVE CHARGES (in e, ~~cummulative~~ output)		BORN EFFECTIVE CHARGES (in e, cumulative output)
	and		and
	PIEZOELECTRIC TENSOR for field in x, y, z (C/m^2)		PIEZOELECTRIC TENSOR for field in x, y, z (C/m^2)
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	We do not recommend to select {{TAG\|LOPTICS}}=.TRUE. and {{TAG\|LEPSILON}}=.TRUE.		We do not recommend to select {{TAG\|LOPTICS}}=.TRUE. and {{TAG\|LEPSILON}}=.TRUE.
	in a single run (although it might work in some versions).		in a single run (although it might work in some versions).
	Density functional perturbation theory {{TAG\|LEPSILON}}=.TRUE. does not require to increase {{TAG\|NBANDS}} and is, in fact, much slower if {{TAG\|NBANDS}} is increased, whereas the summation over ~~emtpy~~ conduction band states requires a large number of such states.		Density functional perturbation theory {{TAG\|LEPSILON}}=.TRUE. does not require to increase {{TAG\|NBANDS}} and is, in fact, much slower if {{TAG\|NBANDS}} is increased, whereas the summation over empty conduction band states requires a large number of such states.

	== Related tags and articles ==		== Related tags and articles ==
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	== References ==		== References ==
	~~<references>~~
	~~<ref name="gajdos:prb:06">[http://link.aps.org/doi/10.1103/PhysRevB.73.045112 M. Gajdoš, K. Hummer, G. Kresse, J. Furthmüller, and F. Bechstedt, Phys. Rev. B 73, 045112 (2006).]</ref>~~
	~~<ref name="baroni:prb:86">[http://link.aps.org/doi/10.1103/PhysRevB.33.7017 S. Baroni and R. Resta, Phys. Rev. B 33, 7017, (1986).]</ref>~~
	~~</references>~~
	~~----~~

	[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric properties]]		[[Category:INCAR tag]][[Category:Linear response]][[Category:Dielectric properties]]