BSEPREC - Revision history

Huebsch: /* Related tag and articles */

2025-10-17T08:53:06Z

Pmelo: /* Lanczos algorithm */

2025-10-16T12:43:27Z

Lanczos algorithm

← Older revision		Revision as of 12:43, 16 October 2025
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	==Lanczos algorithm==		==Lanczos algorithm==
			{{NB\|mind\|Replaces {{TAG\|LANCZOSTHR}} as of version 6.5.1}}
	The Lanczos algorithm stops once the imaginary part of the dielectric function computed in two consecutive iterations differs bellow a certain threshold for the root-mean-square, i.e. once after <math>n</math> iterations the value of		The Lanczos algorithm stops once the imaginary part of the dielectric function computed in two consecutive iterations differs bellow a certain threshold for the root-mean-square, i.e. once after <math>n</math> iterations the value of

Huebsch at 07:46, 16 October 2025

2025-10-16T07:46:30Z

← Older revision		Revision as of 07:46, 16 October 2025
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	{{TAGDEF\|BSEPREC\|Low {{!}} Medium {{!}} High {{!}} Accurate \| Medium}}		{{TAGDEF\|BSEPREC\|Low {{!}} Medium {{!}} High {{!}} Accurate \| Medium}}

	Description: ~~{{TAG\|BSEPREC}} determines~~ the precision of the time-evolution ~~and Lanczos algorithms for solving the Bethe-Salpeter or Casida equations. For the former~~ it controls the timestep and the number of steps, ~~while for~~ the ~~latter~~ it ~~controls~~ the convergence threshold for the dielectric function.		Description: Determines the precision of the [[:Category:Bethe-Salpeter_equations#Time_evolution\|time-evolution algorithm]], where it controls the timestep and the number of steps, and the precision of the [[:Category:Bethe-Salpeter_equations#Lanczos_algorithm \|Lanczos algorithms]], where it sets the convergence threshold for the dielectric function.

			-----

	==Time-evolution algorithm==		==Time-evolution algorithm==
	The timestep in the time-evolution calculation is inversely proportional to the maximum transition energy {{TAG\|OMEGAMAX}} and the number of steps is inversely proportional to the broadening {{TAG\|CSHIFT}}. Depending on the {{TAG\|BSEPREC}} stable these parameters are scaled depending on the precision tag {{TAG\|BSEPREC}}.		The timestep in the time-evolution calculation is inversely proportional to the maximum transition energy {{TAG\|OMEGAMAX}} and the number of steps is inversely proportional to the broadening {{TAG\|CSHIFT}}. Depending on the {{TAG\|BSEPREC}} stable these parameters are scaled depending on the precision tag {{TAG\|BSEPREC}}.

	{\| cellpadding="5" cellspacing="0" border="1"		::{\| cellpadding="5" cellspacing="5" style="width: 50%; border-spacing: 5px;"
	! BSEPREC !! OMEGAMAX !! CSHIFT		\| style="text-align:center; background-color:#DEC4EB;"\| {{TAG\|BSEPREC}} \|\| style="text-align:center; background-color:#DEC4EB;"\| {{TAG\|OMEGAMAX}} \|\| style="text-align:center; background-color:#DEC4EB;"\| {{TAG\|CSHIFT}}
	\|-		\|-
	\| Accurate (a) \|\| <math>\times 4</math> \|\| <math>\times 1/10</math>		\|style="background-color:#D9F8F5;"\| Accurate (a) \|\|style="background-color:#D9F8F5;"\| <math>\times 4</math> \|\|style="background-color:#D9F8F5;"\| <math>\times 1/10</math>
	\|-		\|-
	\| High (h) \|\| <math>\times 3</math> \|\| <math>\times 1/7.5</math>		\|style="background-color:#D9F8F5;"\| High (h) \|\|style="background-color:#D9F8F5;"\| <math>\times 3</math> \|\|style="background-color:#D9F8F5;"\| <math>\times 1/7.5</math>
	\|-		\|-
	\| Medium (m) \|\| <math>\times 2.5</math> \|\| <math>\times1/6.25</math>		\|style="background-color:#D9F8F5;"\| Medium (m) \|\|style="background-color:#D9F8F5;"\| <math>\times 2.5</math> \|\|style="background-color:#D9F8F5;"\| <math>\times1/6.25</math>
	\|-		\|-
	\| Low (l) \|\| <math>\times 2</math> \|\| <math>\times1/5</math>		\|style="background-color:#D9F8F5;"\| Low (l) \|\|style="background-color:#D9F8F5;"\| <math>\times 2</math> \|\|style="background-color:#D9F8F5;"\| <math>\times1/5</math>
	\|}		\|}

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	The Lanczos algorithm stops once the imaginary part of the dielectric function computed in two consecutive iterations differs bellow a certain threshold for the root-mean-square, i.e. once after <math>n</math> iterations the value of		The Lanczos algorithm stops once the imaginary part of the dielectric function computed in two consecutive iterations differs bellow a certain threshold for the root-mean-square, i.e. once after <math>n</math> iterations the value of

	<math>		::<math>
	\mathrm{RMS}[\epsilon_n] = \sqrt{\frac{1}{N_\omega}\sum_{i=1}^{N_\omega}\left(\Im[\epsilon_n(\omega_i)]-\Im[\epsilon_{n-1}(\omega_i)]\right)^2}		\mathrm{RMS}[\epsilon_n] = \sqrt{\frac{1}{N_\omega}\sum_{i=1}^{N_\omega}\left(\Im[\epsilon_n(\omega_i)]-\Im[\epsilon_{n-1}(\omega_i)]\right)^2}
	</math>		</math>

	is below a certain value defined by '''BSEPREC'''.		is below a certain value defined by '''BSEPREC'''.
	{\| cellpadding="5" cellspacing="0" border="1"
	! BSEPREC !! <math>\mathrm{RMS}[\epsilon_n]</math>		::{\| cellpadding="5" cellspacing="5" style="width: 50%; border-spacing: 5px;"
			\| style="text-align:center; background-color:#DEC4EB;"\| BSEPREC \|\| style="text-align:center; background-color:#DEC4EB;"\| <math>\mathrm{RMS}[\epsilon_n]</math>
	\|-		\|-
	\| Accurate (a) \|\| <math>10^{-5}</math>		\|style="background-color:#D9F8F5;"\| Accurate (a) \|\|style="background-color:#D9F8F5;"\| <math>10^{-5}</math>
	\|-		\|-
	\| High (h) \|\| <math>10^{-4}</math>		\|style="background-color:#D9F8F5;"\| High (h) \|\|style="background-color:#D9F8F5;"\| <math>10^{-4}</math>
	\|-		\|-
	\| Medium (m) \|\| <math>10^{-3}</math>		\|style="background-color:#D9F8F5;"\| Medium (m) \|\|style="background-color:#D9F8F5;"\| <math>10^{-3}</math>
	\|-		\|-
	\| Low (l) \|\| <math>10^{-2}</math>		\|style="background-color:#D9F8F5;"\| Low (l) \|\|style="background-color:#D9F8F5;"\| <math>10^{-2}</math>
	\|}		\|}

Pmelo at 14:18, 15 October 2025

2025-10-15T14:18:34Z

@@ Line 1: / Line 1: @@
 {{TAGDEF|BSEPREC|Low {{!}} Medium {{!}} High {{!}}  Accurate | Medium}}
-Description: {{TAG|BSEPREC}} determines the precision of the time-evolution algorithm for solving the Bethe-Salpeter or Casida equations, i.e., the timestep and the number of steps.
+Description: {{TAG|BSEPREC}} determines the precision of the time-evolution and Lanczos algorithms for solving the Bethe-Salpeter or Casida equations. For the former it controls the timestep and the number of steps, while for the latter it controls the convergence threshold for the dielectric function.
-----
+==Time-evolution algorithm==
 The timestep in the time-evolution calculation is inversely proportional to the maximum transition energy {{TAG|OMEGAMAX}} and the number of steps is inversely proportional to the broadening {{TAG|CSHIFT}}. Depending on the {{TAG|BSEPREC}}  stable these parameters are scaled depending on the precision tag {{TAG|BSEPREC}}.
@@ Line 19: / Line 19: @@
 For example, the number of steps <math>N_{\rm steps}</math> for {{TAG|BSEPREC}} = Low can be found via <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}/5}</math>
 == Related tag and articles ==
 {{TAG|IBSE}},

Tal: Tal moved page Construction:BSEPREC to BSEPREC

2023-10-20T11:59:47Z

Tal moved page Construction:BSEPREC to BSEPREC

← Older revision

Revision as of 11:59, 20 October 2023

Tal at 11:56, 20 October 2023

2023-10-20T11:56:41Z

← Older revision		Revision as of 11:56, 20 October 2023
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	[[Time-dependent density-functional theory calculations]],		[[Time-dependent density-functional theory calculations]],
	[[Bethe-Salpeter equations]]		[[Bethe-Salpeter equations]]


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

	[[Category:INCAR tag]] [[Category:Many-body perturbation theory]][[Category:Bethe-Salpeter equations]]		[[Category:INCAR tag]] [[Category:Many-body perturbation theory]][[Category:Bethe-Salpeter equations]]

Tal at 11:56, 20 October 2023

2023-10-20T11:56:07Z

← Older revision		Revision as of 11:56, 20 October 2023
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	The timestep in the time-evolution calculation is inversely proportional to the maximum transition energy {{TAG\|OMEGAMAX}} and the number of steps is inversely proportional to the broadening {{TAG\|CSHIFT}}. Depending on the {{TAG\|BSEPREC}} stable these parameters are scaled depending on the precision tag {{TAG\|BSEPREC}}.		The timestep in the time-evolution calculation is inversely proportional to the maximum transition energy {{TAG\|OMEGAMAX}} and the number of steps is inversely proportional to the broadening {{TAG\|CSHIFT}}. Depending on the {{TAG\|BSEPREC}} stable these parameters are scaled depending on the precision tag {{TAG\|BSEPREC}}.

	::{\| cellpadding="5" cellspacing="0" border="1"		{\| cellpadding="5" cellspacing="0" border="1"
	! BSEPREC !! OMEGAMAX !! CSHIFT		! BSEPREC !! OMEGAMAX !! CSHIFT
	\|-		\|-

Tal at 11:55, 20 October 2023

2023-10-20T11:55:09Z

← Older revision		Revision as of 11:55, 20 October 2023
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	\|}		\|}

	For example, the number of steps <math>N_{\rm steps}</math> for {{TAG\|BSEPREC}} = Low can be found via <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}~~\times5^{-1}~~}</math>		For example, the number of steps <math>N_{\rm steps}</math> for {{TAG\|BSEPREC}} = Low can be found via <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}/5}</math>
	== Related tag and articles ==		== Related tag and articles ==
	{{TAG\|IBSE}},		{{TAG\|IBSE}},
	[[BSE calculations]]		{{TAG\|NBANDSV}},
			{{TAG\|NBANDSO}},
			{{TAG\|CSHIFT}},
			{{TAG\|OMEGAMAX}},
			[[BSE calculations]],
			[[Time-dependent density-functional theory calculations]],
			[[Bethe-Salpeter equations]]


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

Tal at 10:25, 20 October 2023

2023-10-20T10:25:22Z

← Older revision		Revision as of 10:25, 20 October 2023
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	For example, the number of steps <math>N_{\rm steps}</math> for {{TAG\|BSEPREC}} = Low can be found via <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}\times5^{-1}}</math>		For example, the number of steps <math>N_{\rm steps}</math> for {{TAG\|BSEPREC}} = Low can be found via <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}\times5^{-1}}</math>

	== Related tag and articles ==		== Related tag and articles ==
	{{TAG\|IBSE}},		{{TAG\|IBSE}},

Tal at 10:18, 20 October 2023

2023-10-20T10:18:25Z

← Older revision		Revision as of 10:18, 20 October 2023
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	{{TAGDEF\|BSEPREC\|Low {{!}} Medium {{!}} High {{!}} Accurate \| Medium}}		{{TAGDEF\|BSEPREC\|Low {{!}} Medium {{!}} High {{!}} Accurate \| Medium}}


	Description: {{TAG\|BSEPREC}} determines the precision of the time-evolution algorithm for solving the Bethe-Salpeter or Casida equations, i.e., the timestep and the number of steps.		Description: {{TAG\|BSEPREC}} determines the precision of the time-evolution algorithm for solving the Bethe-Salpeter or Casida equations, i.e., the timestep and the number of steps.
Line 19:		Line 18:
	\|}		\|}

	For example, the number of steps for {{TAG\|BSEPREC}} = Low can be found <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}\times5^{-1}}</math>		For example, the number of steps <math>N_{\rm steps}</math> for {{TAG\|BSEPREC}} = Low can be found via <math>N_{\rm steps}=\frac{{\rm OMEGAMAX}\times 2}{{\rm CSHIFT}\times5^{-1}}</math>



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

← Older revision		Revision as of 08:53, 17 October 2025
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	{{TAG\|NBANDSO}},		{{TAG\|NBANDSO}},
	{{TAG\|CSHIFT}},		{{TAG\|CSHIFT}},
	{{TAG\|OMEGAMAX}},		{{TAG\|OMEGAMAX}}
	[[BSE calculations]],
	[[Time-dependent density-functional theory calculations]],		[[BSE calculations]]

			[[Time-dependent density-functional theory calculations]]

	[[Bethe-Salpeter equations]]		[[Bethe-Salpeter equations]]

	----		----
	[[Category:INCAR tag]] [[Category:Many-body perturbation theory]][[Category:Bethe-Salpeter equations]]		[[Category:INCAR tag]] [[Category:Many-body perturbation theory]][[Category:Bethe-Salpeter equations]]