NBANDSV - Revision history

Tal at 11:24, 24 June 2022

2022-06-24T11:24:47Z

← Older revision		Revision as of 11:24, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}

	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

Tal at 11:24, 24 June 2022

2022-06-24T11:24:36Z

← Older revision		Revision as of 11:24, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
	~~{{DEF\|NBANDSV\|number of occupied orbitals\|}}~~
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

Tal at 11:09, 24 June 2022

2022-06-24T11:09:04Z

← Older revision		Revision as of 11:09, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
	{{DEF\|NBANDSV\|number of ~~empty orbtials~~\|}}		{{DEF\|NBANDSV\|number of occupied orbitals\|}}
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

Tal at 09:18, 24 June 2022

2022-06-24T09:18:19Z

← Older revision		Revision as of 09:18, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
	{{DEF\|NBANDSV\|number of empty ~~states~~\|}}		{{DEF\|NBANDSV\|number of empty orbtials\|}}
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

Tal at 09:16, 24 June 2022

2022-06-24T09:16:02Z

← Older revision		Revision as of 09:16, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
			{{DEF\|NBANDSV\|number of empty states\|}}
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

Huebsch at 12:28, 7 April 2022

2022-04-07T12:28:22Z

← Older revision		Revision as of 12:28, 7 April 2022
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	----		----

	For the ~~timepropagation~~ algorithm increasing {{TAG\|NBANDSV}} only modestly increases the compute time.		For the time-propagation algorithm increasing {{TAG\|NBANDSV}} only modestly increases the compute time.
	For BSE and Casida type calculations, the compute time grows with the third power of the number of included occupied and unoccupied bands		For BSE and Casida type calculations, the compute time grows with the third power of the number of included occupied and unoccupied bands

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	<math> (N_{\mathrm{occ}}N_{\mathrm{virtual}} N_{\mathrm{k}})^{2} </math>		<math> (N_{\mathrm{occ}}N_{\mathrm{virtual}} N_{\mathrm{k}})^{2} </math>

	Please be aware that symmetry is not exploited in the BSE code, hence memory requirements can be excessive. To allow for calculations on large systems, the BSE code distributes the BSE matrix among all available cores, and uses ~~scaLAPACK~~ for the diagonalization.		Please be aware that symmetry is not exploited in the BSE code, hence memory requirements can be excessive. To allow for calculations on large systems, the BSE code distributes the BSE matrix among all available cores and uses ScaLAPACK for the diagonalization.

	VASP always uses the orbitals closest to the Fermi-level, and {{TAG\|NBANDSO}} (<math>N_{\mathrm{occ}}</math>) and {{TAG\|NBANDSV}} (<math>N_{\mathrm{virtual}}</math>) determines how many occupied and unoccupied orbitals are included. The defaults are fairly "conservative" and equal the total number of electrons/2 (this usually implies that all occupied state are included). For highly accurate results, {{TAG\|NBANDSV}} often needs to be increased, whereas for large systems one is often forced to reduce both values to much smaller numbers. Sometimes qualitative results for ~~band like~~ Wannier-Mott excitons can be obtained even with a single conduction and valence band.		VASP always uses the orbitals closest to the Fermi-level, and {{TAG\|NBANDSO}} (<math>N_{\mathrm{occ}}</math>) and {{TAG\|NBANDSV}} (<math>N_{\mathrm{virtual}}</math>) determines how many occupied and unoccupied orbitals are included. The defaults are fairly "conservative" and equal the total number of electrons/2 (this usually implies that all occupied state are included). For highly accurate results, {{TAG\|NBANDSV}} often needs to be increased, whereas for large systems one is often forced to reduce both values to much smaller numbers. Sometimes qualitative results for bandlike Wannier-Mott excitons can be obtained even with a single conduction and valence band.

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tag and articles ==
	{{TAG\|NBANDSO}},		{{TAG\|NBANDSO}},
	[[BSE calculations]],		[[BSE calculations]],
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	----		----

	[[Category:INCAR]] [[Category:Many-~~Body Perturbation Theory~~]][[Category:~~BSE~~]]		[[Category:INCAR tag]] [[Category:Many-body perturbation theory]][[Category:Bethe-Salpeter equations]]

Karsai at 15:06, 11 March 2019

2019-03-11T15:06:36Z

← Older revision		Revision as of 15:06, 11 March 2019
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	{{sc\|NBANDSV\|Examples\|Examples that use this tag}}		{{sc\|NBANDSV\|Examples\|Examples that use this tag}}
	----		----

	~~[[The_VASP_Manual\|Contents]]~~

	[[Category:INCAR]] [[Category:Many-Body Perturbation Theory]][[Category:BSE]]		[[Category:INCAR]] [[Category:Many-Body Perturbation Theory]][[Category:BSE]]

Karsai at 14:53, 11 March 2019

2019-03-11T14:53:32Z

← Older revision		Revision as of 14:53, 11 March 2019
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	[[The_VASP_Manual\|Contents]]		[[The_VASP_Manual\|Contents]]

	[[Category:INCAR]] [[Category:BSE]]		[[Category:INCAR]] [[Category:Many-Body Perturbation Theory]][[Category:BSE]]

Kresse: /* Related Tags and Sections */

2018-03-28T13:39:52Z

Related Tags and Sections

← Older revision		Revision as of 13:39, 28 March 2018
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	== Related Tags and Sections ==		== Related Tags and Sections ==
	{{TAG\|NBANDSO}},		{{TAG\|NBANDSO}},
	~~{{TAG\|~~BSE calculations}}		[[BSE calculations]],
			[[timepropagation]]

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

Kresse at 13:38, 28 March 2018

2018-03-28T13:38:10Z

← Older revision		Revision as of 13:38, 28 March 2018
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	----		----

	~~The~~ compute time ~~for~~ BSE and ~~Cassida~~ type calculations grows with the third power of the number of included occupied and unoccupied bands		For the timepropagation algorithm increasing {{TAG\|NBANDSV}} only modestly increases the compute time.
			For BSE and Casida type calculations, the compute time grows with the third power of the number of included occupied and unoccupied bands

	<math> (N_{\mathrm{occ}} N_{\mathrm{virtual}} N_{\mathrm{k}})^{3} </math>		<math> (N_{\mathrm{occ}} N_{\mathrm{virtual}} N_{\mathrm{k}})^{3} </math>

← Older revision		Revision as of 11:24, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
	~~{{DEF\|NBANDSV\|number of occupied orbitals\|}}~~
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

← Older revision		Revision as of 11:09, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
	{{DEF\|NBANDSV\|number of ~~empty orbtials~~\|}}		{{DEF\|NBANDSV\|number of occupied orbitals\|}}
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

← Older revision		Revision as of 09:18, 24 June 2022
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	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
	{{DEF\|NBANDSV\|number of empty ~~states~~\|}}		{{DEF\|NBANDSV\|number of empty orbtials\|}}
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].

← Older revision		Revision as of 09:16, 24 June 2022
Line 1:		Line 1:
	{{TAGDEF\|NBANDSV\|[integer]}}		{{TAGDEF\|NBANDSV\|[integer]}}
			{{DEF\|NBANDSV\|number of empty states\|}}
	Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].		Description: {{TAG\|NBANDSV}} determines how many unoccupied orbitals are included in the Casida/[[BSE calculations]] or [[timepropagation]].