ISEARCH - Revision history

Huebsch at 07:13, 28 May 2025

2025-05-28T07:13:48Z

← Older revision		Revision as of 07:13, 28 May 2025
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	{{TAGDEF\|ISEARCH\|0 {{!}} 1\|0}}		{{TAGDEF\|ISEARCH\|0 {{!}} 1\|0}}

	Description: Controls the line-search algorithm used during the direct minimization of the electronic structure (~~when~~ {{~~TAG~~\|ALGO}} ~~= All~~).		Description: Controls the line-search algorithm used during the direct minimization of the electronic structure ({{TAGO\|ALGO\|All}}).
	----		----
	*{{TAGO\|ISEARCH\|0}}: Legacy line-search algorithm.		*{{TAGO\|ISEARCH\|0}}: Legacy line-search algorithm.

Huebsch at 07:13, 28 May 2025

2025-05-28T07:13:11Z

← Older revision		Revision as of 07:13, 28 May 2025
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	Description: Controls the line-search algorithm used during the direct minimization of the electronic structure (when {{TAG\|ALGO}} = All).		Description: Controls the line-search algorithm used during the direct minimization of the electronic structure (when {{TAG\|ALGO}} = All).
	----		----
	*{{~~TAG~~\|ISEARCH}} ~~= 0~~: Legacy line-search algorithm.		*{{TAGO\|ISEARCH\|0}}: Legacy line-search algorithm.
	*{{~~TAG~~\|ISEARCH}} ~~= 1~~: Improved line-search algorithm.		*{{TAGO\|ISEARCH\|1}}: Improved line-search algorithm.

	The line search determines the optimal step size along the conjugate gradient search direction. {{TAGO\|ISEARCH\|0}} performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. {{TAGO\|ISEARCH\|1}} introduces a more robust and consistent method for determining the optimal step size, leading to improved convergence behavior and more reliable energy minimization.		The line search determines the optimal step size along the conjugate gradient search direction. {{TAGO\|ISEARCH\|0}} performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. {{TAGO\|ISEARCH\|1}} introduces a more robust and consistent method for determining the optimal step size, leading to improved convergence behavior and more reliable energy minimization.

Huebsch at 07:08, 28 May 2025

2025-05-28T07:08:26Z

← Older revision		Revision as of 07:08, 28 May 2025
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	{{TAGDEF\|ISEARCH\|0 {{!}} 1\|0}}		{{TAGDEF\|ISEARCH\|0 {{!}} 1\|0}}

	Description: ~~{{TAG\|ISEARCH}} controls~~ the line search algorithm used during the direct minimization of the electronic structure (when {{TAG\|ALGO}} = A).		Description: Controls the line-search algorithm used during the direct minimization of the electronic structure (when {{TAG\|ALGO}} = All).
	----		----
	*{{TAG\|ISEARCH}} = 0: Legacy line search algorithm.		*{{TAG\|ISEARCH}} = 0: Legacy line-search algorithm.
	*{{TAG\|ISEARCH}} = 1: Improved line search algorithm.		*{{TAG\|ISEARCH}} = 1: Improved line-search algorithm.

	The line search determines the optimal step size along the conjugate gradient search direction. ~~<code>~~{{TAGO\|ISEARCH}} ~~= 0</code>~~ performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. ~~<code>~~{{TAGO\|ISEARCH}} ~~= 1</code>~~ introduces a more robust and consistent method for determining the optimal step size, ~~resulting in better~~ convergence behavior and more reliable energy minimization.		The line search determines the optimal step size along the conjugate gradient search direction. {{TAGO\|ISEARCH\|0}} performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. {{TAGO\|ISEARCH\|1}} introduces a more robust and consistent method for determining the optimal step size, leading to improved convergence behavior and more reliable energy minimization.
	{{NB\|important\|~~It is recommended to use <code>~~{{TAGO\|ISEARCH}} ~~{{=}} 1</code>~~ when performing electronic minimizations with <code>{{TAGO\|ALGO}} {{=}} A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps~~, i~~.~~e., <code>ALGO {{=}} A; ISEARCH {{=}} 1 </code>~~}}		{{NB\|important\|We recommend {{TAGO\|ISEARCH\|1}} when performing electronic minimizations with <code>{{TAGO\|ALGO}} {{=}} All</code>, as it generally improves convergence stability and reduces the total number of required SCF steps.}}
	{{NB\|mind\|~~<code>~~{{TAGO\|ISEARCH}} ~~{{=}} 0</code>~~ should only be used for backward compatibility or benchmarking against legacy behavior.}}		{{NB\|mind\|{{TAGO\|ISEARCH\|0}} should only be used for backward compatibility or benchmarking against legacy behavior.}}

	== Improved line search algorithm ==		== Improved line-search algorithm ==

	The improved algorithm (~~enabled with <code>~~{{TAGO\|ISEARCH}} ~~= 1</code>~~) introduces several enhancements over the legacy implementation:		The improved algorithm ({{TAGO\|ISEARCH\|1}}) introduces several enhancements over the legacy implementation:
	*'''Absolute reference''' - each line search step starts from the origin of the search direction rather than progressing incrementally. This improves energy consistency.		*'''Absolute reference''' - each line search step starts from the origin of the search direction rather than progressing incrementally. This improves energy consistency.
	*'''Efficient slot system''' - all trial steps are stored in slots, reducing redundant energy evaluations.		*'''Efficient slot system''' - all trial steps are stored in slots, reducing redundant energy evaluations.
	*'''Minimum acceptance criterion''' - the final energy minimum of the line search is accepted only if its neighboring slots have also been evaluated (first principles energies are known), ensuring reliable interpolation.		*'''Minimum-acceptance criterion''' - the final energy minimum of the line search is accepted only if its neighboring slots have also been evaluated (first principles energies are known), ensuring reliable interpolation.
	*'''Polynomial and spline fitting'''		*'''Polynomial and spline fitting'''
	**If ≤ 5 data points are available, an up to 4th-order polynomial fit is used to determine the minimum.		**If ≤ 5 data points are available, an up to 4th-order polynomial fit is used to determine the minimum.
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	== Related tags and articles ==		== Related tags and articles ==
	{{TAG\|ALGO}}		{{TAG\|ALGO}}

	~~{{sc\|ISEARCH\|Examples\|Examples that use this tag}}~~

	[[Category:INCAR tag]][[Category:Electronic minimization]]		[[Category:INCAR tag]][[Category:Electronic minimization]]

Csheldon at 14:27, 27 May 2025

2025-05-27T14:27:31Z

← Older revision		Revision as of 14:27, 27 May 2025
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	The line search determines the optimal step size along the conjugate gradient search direction. <code>{{TAGO\|ISEARCH}} = 0</code> performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. <code>{{TAGO\|ISEARCH}} = 1</code> introduces a more robust and consistent method for determining the optimal step size, resulting in better convergence behavior and more reliable energy minimization.		The line search determines the optimal step size along the conjugate gradient search direction. <code>{{TAGO\|ISEARCH}} = 0</code> performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. <code>{{TAGO\|ISEARCH}} = 1</code> introduces a more robust and consistent method for determining the optimal step size, resulting in better convergence behavior and more reliable energy minimization.
			{{NB\|important\|It is recommended to use <code>{{TAGO\|ISEARCH}} {{=}} 1</code> when performing electronic minimizations with <code>{{TAGO\|ALGO}} {{=}} A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps, i.e., <code>ALGO {{=}} A; ISEARCH {{=}} 1 </code>}}
			{{NB\|mind\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}

	== ~~Description of the~~ Improved ~~Algorithm~~ ==		== Improved line search algorithm ==

	The improved algorithm (enabled with <code>{{TAGO\|ISEARCH}} = 1</code>) introduces several enhancements over the legacy implementation:		The improved algorithm (enabled with <code>{{TAGO\|ISEARCH}} = 1</code>) introduces several enhancements over the legacy implementation:
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	**If > 5 data points are available, a spline interpolation is used instead, offering greater robustness than higher-order polynomials.		**If > 5 data points are available, a spline interpolation is used instead, offering greater robustness than higher-order polynomials.
	*'''Gradient correction''' - the line search typically relies on total energy evaluations only, which is faster than computing gradients. If the new gradient is not sufficiently orthogonal to the search direction from the previous step, a correction is applied using all available data points (via polynomial or spline fit).		*'''Gradient correction''' - the line search typically relies on total energy evaluations only, which is faster than computing gradients. If the new gradient is not sufficiently orthogonal to the search direction from the previous step, a correction is applied using all available data points (via polynomial or spline fit).

	~~== Recommendations ==~~
	It is recommended to use <code>{{TAGO\|ISEARCH}} = 1</code> when performing electronic minimizations with <code>{{TAGO\|ALGO}} = A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps, e.g.:
	~~ALGO = A; ISEARCH = 1~~
	~~{{NB\|mind\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}~~

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

Csheldon: /* Recommendations */

2025-05-27T14:22:41Z

Recommendations

← Older revision		Revision as of 14:22, 27 May 2025
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	== Recommendations ==		== Recommendations ==
	It is recommended to use <code>{{TAGO\|ISEARCH}} = 1</code> when performing electronic minimizations with <code>{{TAGO\|ALGO}} = A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps, e.g.:		It is recommended to use <code>{{TAGO\|ISEARCH}} = 1</code> when performing electronic minimizations with <code>{{TAGO\|ALGO}} = A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps, e.g.:

	ALGO = A; ISEARCH = 1		ALGO = A; ISEARCH = 1

	{{NB\|mind\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}		{{NB\|mind\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}

Csheldon: /* Recommendations */

2025-05-27T14:22:30Z

Recommendations

← Older revision		Revision as of 14:22, 27 May 2025
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	ALGO = A; ISEARCH = 1		ALGO = A; ISEARCH = 1

	{{NB\|~~Mind~~\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}		{{NB\|mind\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}

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

Csheldon: /* Recommendations */

2025-05-27T14:22:22Z

Recommendations

← Older revision		Revision as of 14:22, 27 May 2025
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	ALGO = A; ISEARCH = 1		ALGO = A; ISEARCH = 1

	<code>{{TAGO\|ISEARCH}} = 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.		{{NB\|Mind\|<code>{{TAGO\|ISEARCH}} {{=}} 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.}}

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

Csheldon at 14:21, 27 May 2025

2025-05-27T14:21:59Z

← Older revision		Revision as of 14:21, 27 May 2025
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	== Recommendations ==		== Recommendations ==
	It is recommended to use <code>{{TAGO\|ISEARCH}} = 1</code> when performing electronic minimizations with <code>{{TAGO\|ALGO}} = A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps. ~~<code>{{TAGO\|ISEARCH}} = 0</code> should only be used for backward compatibility or benchmarking against legacy behavior~~.		It is recommended to use <code>{{TAGO\|ISEARCH}} = 1</code> when performing electronic minimizations with <code>{{TAGO\|ALGO}} = A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps, e.g.:

	== ~~Example ==~~		ALGO = A; ISEARCH = 1

	~~ALGO = A~~		<code>{{TAGO\|ISEARCH}} = 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.
	ISEARCH = 1

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

Csheldon: Csheldon moved page Construction:ISEARCH to ISEARCH

2025-05-27T14:20:30Z

Csheldon moved page Construction:ISEARCH to ISEARCH

← Older revision	Revision as of 14:20, 27 May 2025
(No difference)

Csheldon: Created page with "{{TAGDEF|ISEARCH|0 {{!}} 1|0}} Description: {{TAG|ISEARCH}} controls the line search algorithm used during the direct minimization of the electronic structure (when {{TAG|ALGO}} = A). ---- {{TAG|ISEARCH}} = 0: Legacy line search algorithm. {{TAG|ISEARCH}} = 1: Improved line search algorithm. The line search determines the optimal step size along the conjugate gradient search direction. `{{TAGO|ISEARCH}} = 0` performs incremental steps along the search dire..."

2025-05-27T14:17:13Z

Created page with "{{TAGDEF|ISEARCH|0 {{!}} 1|0}} Description: {{TAG|ISEARCH}} controls the line search algorithm used during the direct minimization of the electronic structure (when {{TAG|ALGO}} = A). ---- *{{TAG|ISEARCH}} = 0: Legacy line search algorithm. *{{TAG|ISEARCH}} = 1: Improved line search algorithm. The line search determines the optimal step size along the conjugate gradient search direction. <code>{{TAGO|ISEARCH}} = 0</code> performs incremental steps along the search dire..."

New page

{{TAGDEF|ISEARCH|0 {{!}} 1|0}}

Description: {{TAG|ISEARCH}} controls the line search algorithm used during the direct minimization of the electronic structure (when {{TAG|ALGO}} = A).
----
*{{TAG|ISEARCH}} = 0: Legacy line search algorithm.
*{{TAG|ISEARCH}} = 1: Improved line search algorithm.

The line search determines the optimal step size along the conjugate gradient search direction. <code>{{TAGO|ISEARCH}} = 0</code> performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. <code>{{TAGO|ISEARCH}} = 1</code> introduces a more robust and consistent method for determining the optimal step size, resulting in better convergence behavior and more reliable energy minimization.

== Description of the Improved Algorithm ==

The improved algorithm (enabled with <code>{{TAGO|ISEARCH}} = 1</code>) introduces several enhancements over the legacy implementation:
*'''Absolute reference''' - each line search step starts from the origin of the search direction rather than progressing incrementally. This improves energy consistency.
*'''Efficient slot system''' - all trial steps are stored in slots, reducing redundant energy evaluations.
*'''Minimum acceptance criterion''' - the final energy minimum of the line search is accepted only if its neighboring slots have also been evaluated (first principles energies are known), ensuring reliable interpolation.
*'''Polynomial and spline fitting'''
**If ≤ 5 data points are available, an up to 4th-order polynomial fit is used to determine the minimum.
**If > 5 data points are available, a spline interpolation is used instead, offering greater robustness than higher-order polynomials.
*'''Gradient correction''' - the line search typically relies on total energy evaluations only, which is faster than computing gradients. If the new gradient is not sufficiently orthogonal to the search direction from the previous step, a correction is applied using all available data points (via polynomial or spline fit).

== Recommendations ==
It is recommended to use <code>{{TAGO|ISEARCH}} = 1</code> when performing electronic minimizations with <code>{{TAGO|ALGO}} = A</code>, as it generally improves convergence stability and reduces the total number of required SCF steps. <code>{{TAGO|ISEARCH}} = 0</code> should only be used for backward compatibility or benchmarking against legacy behavior.

== Example ==

ALGO = A
ISEARCH = 1

== Related tags and articles ==
{{TAG|ALGO}}

{{sc|ISEARCH|Examples|Examples that use this tag}}

[[Category:INCAR tag]][[Category:Electronic minimization]]

← Older revision		Revision as of 07:13, 28 May 2025
Line 3:		Line 3:
	Description: Controls the line-search algorithm used during the direct minimization of the electronic structure (when {{TAG\|ALGO}} = All).		Description: Controls the line-search algorithm used during the direct minimization of the electronic structure (when {{TAG\|ALGO}} = All).
	----		----
	*{{~~TAG~~\|ISEARCH}} ~~= 0~~: Legacy line-search algorithm.		*{{TAGO\|ISEARCH\|0}}: Legacy line-search algorithm.
	*{{~~TAG~~\|ISEARCH}} ~~= 1~~: Improved line-search algorithm.		*{{TAGO\|ISEARCH\|1}}: Improved line-search algorithm.

	The line search determines the optimal step size along the conjugate gradient search direction. {{TAGO\|ISEARCH\|0}} performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. {{TAGO\|ISEARCH\|1}} introduces a more robust and consistent method for determining the optimal step size, leading to improved convergence behavior and more reliable energy minimization.		The line search determines the optimal step size along the conjugate gradient search direction. {{TAGO\|ISEARCH\|0}} performs incremental steps along the search direction. It may lead to inconsistencies in total energy evaluations and slower convergence. {{TAGO\|ISEARCH\|1}} introduces a more robust and consistent method for determining the optimal step size, leading to improved convergence behavior and more reliable energy minimization.