OMEGAMAX - Revision history

Hampel at 11:29, 12 August 2025

2025-08-12T11:29:56Z

← Older revision		Revision as of 11:29, 12 August 2025
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	Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for the dense part of the frequency grid for GW calculations (old GW code, does not apply to GWR).		Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for the dense part of the frequency grid for GW calculations (old GW code, does not apply to GWR).
	For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.		For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.
	For BSE calculations {{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).		For BSE calculations {{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included.
			For calculations of the dielectric function via {{TAG\|LOPTICS}} {{TAG\|OMEGAMAX}} determines the maximum frequency of the calculated dielectric properties. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).
	----		----
	GW type calculations:		GW type calculations:
Line 20:		Line 21:
	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the products of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the products of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

			Frequency dependent dielectric matrix calculations (see {{TAG\|LOPTICS}}):

			Here, {{TAG\|OMEGAMAX}} sets the maximum frequency of the dielectric function calculated. The number of grid points is then defined via {{TAG\|NEDOS}}. Note, that this parameter does not cut-off the number conduction/ valence band pairs considered in the dielectric function. Only the dielectric function itself is cut-off at this frequency. Hence, this does not affect computational effort significantly. It is advisable to choose {{TAG\|OMEGAMAX}} high enough such that the excitation spectrum is well covered, to avoid artifacts at the cut off frequency due to the Gaussian and Lorentzian broadening (see section {{TAG\|LOPTICS#Spectral broadening}})

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

Huebsch at 10:25, 19 July 2022

2022-07-19T10:25:13Z

← Older revision		Revision as of 10:25, 19 July 2022
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	----		----

	[[Category:INCAR tag]][[Category:Many-~~Body Perturbation Theory~~]][[Category:GW]]		[[Category:INCAR tag]][[Category:Many-body perturbation theory]][[Category:GW]]

Karsai: /* Related Tags and Sections */

2022-04-08T14:52:26Z

Related Tags and Sections

← Older revision		Revision as of 14:52, 8 April 2022
Line 21:		Line 21:
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|OMEGATL}},		{{TAG\|OMEGATL}},
	{{TAG\|CSHIFT}},		{{TAG\|CSHIFT}},
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	----		----

	[[Category:INCAR]][[Category:Many-Body Perturbation Theory]][[Category:GW]]		[[Category:INCAR tag]][[Category:Many-Body Perturbation Theory]][[Category:GW]]

Kresse at 10:28, 29 January 2021

2021-01-29T10:28:09Z

← Older revision		Revision as of 10:28, 29 January 2021
Line 18:		Line 18:
	BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}):		BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}):

	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the ~~produce~~ of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the products of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

Kresse at 10:22, 29 January 2021

2021-01-29T10:22:49Z

← Older revision		Revision as of 10:22, 29 January 2021
Line 19:		Line 19:

	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function ~~(the~~ real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

	== Related Tags and Sections ==		== Related Tags and Sections ==

Kresse at 10:21, 29 January 2021

2021-01-29T10:21:43Z

← Older revision		Revision as of 10:21, 29 January 2021
Line 16:		Line 16:


	BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}:		BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}):

	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than

Kresse at 10:21, 29 January 2021

2021-01-29T10:21:28Z

← Older revision		Revision as of 10:21, 29 January 2021
Line 16:		Line 16:


	BSE and TD-DFT type calculations:		BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}:

	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than

Kresse at 10:20, 29 January 2021

2021-01-29T10:20:53Z

← Older revision		Revision as of 10:20, 29 January 2021
Line 17:		Line 17:

	BSE and TD-DFT type calculations:		BSE and TD-DFT type calculations:

	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function (the real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function (the real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

Kresse at 10:20, 29 January 2021

2021-01-29T10:20:34Z

← Older revision		Revision as of 10:20, 29 January 2021
Line 1:		Line 1:
	{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}		{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}

	Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for dense part of the frequency grid. For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction. For BSE calculations		Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for the dense part of the frequency grid for GW calculations (old GW code, does not apply to GWR).
	{{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).		For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.
			For BSE calculations {{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).
	----		----
			GW type calculations:

	For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.		For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.

Line 11:		Line 14:

	For {{TAG\|LSPECTRAL}} = .TRUE. independent convergence tests with respect to {{TAG\|NOMEGA}} and {{TAG\|CSHIFT}} are usually not required, and it should be sufficient to control the technical parameters via the single parameter {{TAG\|NOMEGA}}. Also note that too large values for {{TAG\|NOMEGA}} in combination with coarse k-point grids can cause a decrease in precision (see {{TAG\|NOMEGA}}).		For {{TAG\|LSPECTRAL}} = .TRUE. independent convergence tests with respect to {{TAG\|NOMEGA}} and {{TAG\|CSHIFT}} are usually not required, and it should be sufficient to control the technical parameters via the single parameter {{TAG\|NOMEGA}}. Also note that too large values for {{TAG\|NOMEGA}} in combination with coarse k-point grids can cause a decrease in precision (see {{TAG\|NOMEGA}}).


			BSE and TD-DFT type calculations:
			In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
			{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function (the real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

	== Related Tags and Sections ==		== Related Tags and Sections ==

Kresse at 10:11, 29 January 2021

2021-01-29T10:11:05Z

← Older revision		Revision as of 10:11, 29 January 2021
Line 1:		Line 1:
	{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}		{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}

	Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for dense part of the frequency grid. For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.		Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for dense part of the frequency grid. For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction. For BSE calculations
			{{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).
	----		----
	For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.		For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.

← Older revision		Revision as of 11:29, 12 August 2025
Line 3:		Line 3:
	Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for the dense part of the frequency grid for GW calculations (old GW code, does not apply to GWR).		Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for the dense part of the frequency grid for GW calculations (old GW code, does not apply to GWR).
	For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.		For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.
	For BSE calculations {{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).		For BSE calculations {{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included.
			For calculations of the dielectric function via {{TAG\|LOPTICS}} {{TAG\|OMEGAMAX}} determines the maximum frequency of the calculated dielectric properties. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).
	----		----
	GW type calculations:		GW type calculations:
Line 20:		Line 21:
	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the products of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the products of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

			Frequency dependent dielectric matrix calculations (see {{TAG\|LOPTICS}}):

			Here, {{TAG\|OMEGAMAX}} sets the maximum frequency of the dielectric function calculated. The number of grid points is then defined via {{TAG\|NEDOS}}. Note, that this parameter does not cut-off the number conduction/ valence band pairs considered in the dielectric function. Only the dielectric function itself is cut-off at this frequency. Hence, this does not affect computational effort significantly. It is advisable to choose {{TAG\|OMEGAMAX}} high enough such that the excitation spectrum is well covered, to avoid artifacts at the cut off frequency due to the Gaussian and Lorentzian broadening (see section {{TAG\|LOPTICS#Spectral broadening}})

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

← Older revision		Revision as of 10:28, 29 January 2021
Line 18:		Line 18:
	BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}):		BSE and TD-DFT type calculations (see {{TAG\| BSE calculations}}):

	In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the ~~produce~~ of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than		In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the products of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
	{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.		{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function. The real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

← Older revision		Revision as of 10:20, 29 January 2021
Line 1:		Line 1:
	{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}		{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}

	Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for dense part of the frequency grid. For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction. For BSE calculations		Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for the dense part of the frequency grid for GW calculations (old GW code, does not apply to GWR).
	{{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).		For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.
			For BSE calculations {{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).
	----		----
			GW type calculations:

	For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.		For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.

Line 11:		Line 14:

	For {{TAG\|LSPECTRAL}} = .TRUE. independent convergence tests with respect to {{TAG\|NOMEGA}} and {{TAG\|CSHIFT}} are usually not required, and it should be sufficient to control the technical parameters via the single parameter {{TAG\|NOMEGA}}. Also note that too large values for {{TAG\|NOMEGA}} in combination with coarse k-point grids can cause a decrease in precision (see {{TAG\|NOMEGA}}).		For {{TAG\|LSPECTRAL}} = .TRUE. independent convergence tests with respect to {{TAG\|NOMEGA}} and {{TAG\|CSHIFT}} are usually not required, and it should be sufficient to control the technical parameters via the single parameter {{TAG\|NOMEGA}}. Also note that too large values for {{TAG\|NOMEGA}} in combination with coarse k-point grids can cause a decrease in precision (see {{TAG\|NOMEGA}}).


			BSE and TD-DFT type calculations:
			In this case, {{TAG\|OMEGAMAX}} allows to reduce the number of conduction/ valence band pairs. Usually these are determined by {{TAG\| NBANDSV}} and {{TAG\| NBANDSO}}. The number of pairs is roughly proportional to the produce of {{TAG\| NBANDSV}}, {{TAG\| NBANDSO}}, and the number of k-points in the full Brillouin zone. If {{TAG\|OMEGAMAX}} is set, pairs for which the difference of the independent particle energy is larger than
			{{TAG\|OMEGAMAX}} will be removed from the basis set (and from the BSE calculations). This can improve performance, without significantly affecting the imaginary part of the dielectric function (the real part of the dielectric function is, however, rather sensitive to reducing {{TAG\|OMEGAMAX}}, {{TAG\|NBANDSV}}, {{TAG\|NBANDSO}}.

	== Related Tags and Sections ==		== Related Tags and Sections ==

← Older revision		Revision as of 10:11, 29 January 2021
Line 1:		Line 1:
	{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}		{{TAGDEF\|OMEGAMAX\|[real]\|outermost node in dielectric function <math>\epsilon(\omega)</math>/1.3}}

	Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for dense part of the frequency grid. For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction.		Description: {{TAG\|OMEGAMAX}} specifies the maximum frequency for dense part of the frequency grid. For CRPA calculations, {{TAG\|OMEGAMAX}} is the frequency point of the interaction. For BSE calculations
			{{TAG\|OMEGAMAX}} determines the maximum energy difference for excitation pairs to be included. Since the flag controls different aspects of the code, be careful when setting it (and remember to remove the tag, when you change the type of calculations).
	----		----
	For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.		For the frequency grid along the real and imaginary axis sophisticated schemes are used, which are based on simple model functions for the macroscopic dielectric function. The grid spacing is dense up to roughly 1.3*{{TAG\|OMEGAMAX}} and becomes coarser for larger frequencies. The default value for {{TAG\|OMEGAMAX}} is either determined by the outermost node in the dielectric function (corresponding to a singularity in the inverse of the dielectric function) or the energy difference between the valence band minimum and the conduction band minimum. The larger of these two values is used. Except for pseudopotentials with deep lying core states, {{TAG\|OMEGAMAX}} is usually determined by the node in the dielectric function.