BANDGAP - Revision history

Huebsch at 10:55, 19 March 2024

2024-03-19T10:55:26Z

← Older revision		Revision as of 10:55, 19 March 2024
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	{{sc\|BANDGAP\|Examples\|Examples that use this tag}}		{{sc\|BANDGAP\|Examples\|Examples that use this tag}}

	~~<!-- Commented out until public~~ [[Category:INCAR tag]][[Category:~~Density of States~~]] ~~-->~~		[[Category:INCAR tag]][[Category:Electronic ground-state properties]]

Huebsch: Huebsch moved page Construction:BANDGAP to BANDGAP without leaving a redirect

2024-03-19T10:54:02Z

Huebsch moved page Construction:BANDGAP to BANDGAP without leaving a redirect

← Older revision	Revision as of 10:54, 19 March 2024
(No difference)

Schlipf at 14:50, 17 October 2023

2023-10-17T14:50:25Z

← Older revision		Revision as of 14:50, 17 October 2023
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	Description: {{TAG\|BANDGAP}} determines the verbosity for reporting the bandgap to the OUTCAR file.		Description: {{TAG\|BANDGAP}} determines the verbosity for reporting the bandgap to the OUTCAR file.
			Only the first character is significant.
	----		----

Schlipf at 14:49, 17 October 2023

2023-10-17T14:49:37Z

← Older revision		Revision as of 14:49, 17 October 2023
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	The column ''spin independent'' is always present and reports the bandgap ignoring the spin of the electron.		The column ''spin independent'' is always present and reports the bandgap ignoring the spin of the electron.
	The other two columns are only visible for {{TAG\|ISPIN}}=2 and describe the bandgap for a given spin of the electron.		The other two columns are only visible for {{TAG\|ISPIN}}=2 and describe the bandgap for a given spin of the electron.
	The first block of rows ~~shows~~ the band edges of the fundamental bandgap and their corresponding '''k'''-point coordinates.		The first block of rows show the band edges of the fundamental bandgap and their corresponding '''k'''-point coordinates.
	The second block reports analogous values for the direct gap.		The second block reports analogous values for the direct gap.
	In each case, the energy difference of the band edges is computed and printed as fundamental and direct gap, respectively.		In each case the energy difference of the band edges is computed and printed as fundamental and direct gap, respectively.

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

Schlipf at 13:44, 17 October 2023

2023-10-17T13:44:10Z

@@ Line 21: / Line 21: @@
 *{{TAG|BANDGAP}}=KPOINT
 : Considers each '''k''' point individually to decide what valence and conduction bands are. Provides a comprehensive report of all band extrema.
 The figure illustrates different possible properties of electronic band structures.
@@ Line 37: / Line 39: @@
 For collinear calculations ({{TAG|ISPIN}}=2), this method will allow for a different number of up and down electrons at every '''k''' point.
 {{NB|mind|Setting {{TAG|BANDGAP}}{{=}}KPOINT only impacts the output of VASP. It is not considered when evaluating the occupations of different bands. If you want to enforce certain occupations, please consider the tags {{TAG|NUPDOWN}}, {{TAG|FERWE}}, and {{TAG|FERDO}}.}}
 == Related tags and articles==
-{{TAG|EFERMI}} {{TAG|ISMEAR}} {{TAG|SIGMA}}
+{{TAG|EFERMI}}, {{TAG|ISMEAR}}, {{TAG|SIGMA}}
 {{sc|BANDGAP|Examples|Examples that use this tag}}
-----
+<!-- Commented out until public [[Category:INCAR tag]][[Category:Density of States]] -->

Schlipf at 13:24, 17 October 2023

2023-10-17T13:24:25Z

← Older revision		Revision as of 13:24, 17 October 2023
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	[[File:bandgap.png\|thumbnail\|400px\|For semiconductors, the direct and fundamental bandgap have a clear definition.		[[File:bandgap.png\|thumbnail\|400px\|For semiconductors, the direct and fundamental bandgap have a clear definition.
	For semimetals, the Fermi energy cuts through bands so ~~the~~ depending on the method one defines either a zero or a negative fundamental bandgap.		For semimetals, the Fermi energy cuts through bands so depending on the method one defines either a zero or a negative fundamental bandgap.
	For metals, defining a bandgap is not meaningful.]]		For metals, defining a bandgap is not meaningful.]]

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	The figure illustrates different possible properties of electronic band structures.		The figure illustrates different possible properties of electronic band structures.
	For semiconductors, the bandgap is well defined so that the choice of {{TAG\|BANDGAP}} only ~~effects~~ whether the output is compact or verbose.		For semiconductors, the bandgap is well defined so that the choice of {{TAG\|BANDGAP}} only affects whether the output is compact or verbose.
	For metals, there is no straightforward definition of a bandgap so ~~that~~ the default of {{TAG\|BANDGAP}}=COMPACT is sufficient.		For metals, there is no straightforward definition of a bandgap so the default of {{TAG\|BANDGAP}}=COMPACT is sufficient.
	A semimetal shares properties with metals (Fermi energy crosses bands) and with semiconductors (visible bandgap in the band structure).		A semimetal shares properties with metals (Fermi energy crosses bands) and with semiconductors (visible bandgap in the band structure).

	{{TAG\|BANDGAP}}=WEIGHT interprets systems like a metal; valence (conduction) states are more (less) than half filled.		{{TAG\|BANDGAP}}=WEIGHT interprets systems like a metal; valence (conduction) states are more (less) than half-filled.
	In this case, the bandgap of a semimetal converges to zero with increasing number of '''k''' points similar to a metal.		In this case, the bandgap of a semimetal converges to zero with an increasing number of '''k''' points similar to a metal.
	For N number of electrons, the number of valence states is not in general equal to N for all '''k''' points.		For N number of electrons, the number of valence states is not in general equal to N for all '''k''' points.
	Hence, the direct bandgap is not necessarily between the N-th and the (N + 1)-th state.		Hence, the direct bandgap is not necessarily between the N-th and the (N + 1)-th state.

Schlipf at 13:21, 17 October 2023

2023-10-17T13:21:17Z

← Older revision		Revision as of 13:21, 17 October 2023
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	----		----

	[[File:bandgap.png\|thumbnail\|400px\|For ~~semiconductor~~, ~~the bandgap~~ the direct and fundamental bandgap have a clear definition.		[[File:bandgap.png\|thumbnail\|400px\|For semiconductors, the direct and fundamental bandgap have a clear definition.
	For semimetals, the Fermi energy cuts through bands so the depending on the method one defines either a zero or a negative fundamental bandgap.		For semimetals, the Fermi energy cuts through bands so the depending on the method one defines either a zero or a negative fundamental bandgap.
	For metals, defining a bandgap is not meaningful.]]		For metals, defining a bandgap is not meaningful.]]

Schlipf at 13:18, 17 October 2023

2023-10-17T13:18:59Z

← Older revision		Revision as of 13:18, 17 October 2023
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	: Considers each '''k''' point individually to decide what valence and conduction bands are. Provides a comprehensive report of all band extrema.		: Considers each '''k''' point individually to decide what valence and conduction bands are. Provides a comprehensive report of all band extrema.

			The figure illustrates different possible properties of electronic band structures.
			For semiconductors, the bandgap is well defined so that the choice of {{TAG\|BANDGAP}} only effects whether the output is compact or verbose.
			For metals, there is no straightforward definition of a bandgap so that the default of {{TAG\|BANDGAP}}=COMPACT is sufficient.
			A semimetal shares properties with metals (Fermi energy crosses bands) and with semiconductors (visible bandgap in the band structure).

			{{TAG\|BANDGAP}}=WEIGHT interprets systems like a metal; valence (conduction) states are more (less) than half filled.
			In this case, the bandgap of a semimetal converges to zero with increasing number of '''k''' points similar to a metal.
			For N number of electrons, the number of valence states is not in general equal to N for all '''k''' points.
			Hence, the direct bandgap is not necessarily between the N-th and the (N + 1)-th state.

			{{TAG\|BANDGAP}}=KPOINT considers systems like a semiconductor where every '''k''' point may be treated individually.
			The number of valence bands is equal to the number of electrons N for all '''k''' points and the direct bandgap is equal to the smallest difference between the N-th and (N + 1)-th state.
			In a semimetal, this approach produces a negative bandgap because the Fermi energy crosses the bands.
			For collinear calculations ({{TAG\|ISPIN}}=2), this method will allow for a different number of up and down electrons at every '''k''' point.
			{{NB\|mind\|Setting {{TAG\|BANDGAP}}{{=}}KPOINT only impacts the output of VASP. It is not considered when evaluating the occupations of different bands. If you want to enforce certain occupations, please consider the tags {{TAG\|NUPDOWN}}, {{TAG\|FERWE}}, and {{TAG\|FERDO}}.}}

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

Schlipf at 12:21, 17 October 2023

2023-10-17T12:21:45Z

← Older revision		Revision as of 12:21, 17 October 2023
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	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR tag]][[Category:Electronic Minimization]][[Category:Density of States]]		<!-- Commented out until public [[Category:INCAR tag]][[Category:Electronic Minimization]][[Category:Density of States]] -->

Schlipf at 12:20, 17 October 2023

2023-10-17T12:20:51Z

← Older revision		Revision as of 12:20, 17 October 2023
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	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR ~~tags~~]][[Category:Electronic Minimization]][[Category:Density of States]]		[[Category:INCAR tag]][[Category:Electronic Minimization]][[Category:Density of States]]