LTEMPER - Revision history

Huebsch at 10:02, 19 November 2025

2025-11-19T10:02:52Z

← Older revision		Revision as of 10:02, 19 November 2025
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	[[Category:INCAR tag]][[Category:~~Parallel Tempering~~]]		[[Category:INCAR tag]][[Category:Advanced molecular-dynamics sampling]]

Karsai: /* References */

2022-04-08T14:43:35Z

References

← Older revision		Revision as of 14:43, 8 April 2022
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	----		----

	[[Category:INCAR]][[Category:Parallel Tempering]]		[[Category:INCAR tag]][[Category:Parallel Tempering]]

Karsai: /* Related Tags and Sections */

2022-04-08T14:43:28Z

Related Tags and Sections

← Older revision		Revision as of 14:43, 8 April 2022
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	The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.2-0.3. If the acceptance ratio is too small, one usually needs to increase the number of images. However, too many images can also decrease the probability that all images visit all allowed temperatures.		The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.2-0.3. If the acceptance ratio is too small, one usually needs to increase the number of images. However, too many images can also decrease the probability that all images visit all allowed temperatures.

	== Related ~~Tags~~ and ~~Sections~~ ==		== Related tags and articles ==
	{{TAG\|IMAGES}},		{{TAG\|IMAGES}},
	{{TAG\|NTEMPER}}		{{TAG\|NTEMPER}}

Kresse at 07:53, 18 March 2022

2022-03-18T07:53:09Z

← Older revision		Revision as of 07:53, 18 March 2022
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	In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every		In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every
	{{TAG\|NTEMPER}} MD steps, and accepted with a likelyhood of		{{TAG\|NTEMPER}} MD steps and accepted with a likelyhood of

	:<math> p = \min \left( 1, \frac{ \exp \left( -\frac{E_j}{kT_i} - \frac{E_i}{kT_j} \right) }{ \exp \left( -\frac{E_i}{kT_i} - \frac{E_j}{kT_j} \right) } \right) = \min \left( 1, e^{(E_i - E_j) \left( \frac{1}{kT_i} - \frac{1}{kT_j} \right)} \right) ,</math>		:<math> p = \min \left( 1, \frac{ \exp \left( -\frac{E_j}{kT_i} - \frac{E_i}{kT_j} \right) }{ \exp \left( -\frac{E_i}{kT_i} - \frac{E_j}{kT_j} \right) } \right) = \min \left( 1, e^{(E_i - E_j) \left( \frac{1}{kT_i} - \frac{1}{kT_j} \right)} \right) ,</math>


	where <math> E_i, E_j</math> and <math> T_i, T_j </math> are the energies and temperatures of the considered two replicas. Note that VASP swaps the temperatures and not the positions between images. This means that the temperatures in each subdirectory ~~changes~~ as the MD progresses. Information on the current temperatures for each image can be found in the {{TAG\|OUTCAR}} files around the lines (all OUTCAR files will show the same information):		where <math> E_i, E_j</math> and <math> T_i, T_j </math> are the energies and temperatures of the considered two replicas. Note that VASP swaps the temperatures and not the positions between images. This means that the temperatures in each subdirectory change as the MD progresses. Information on the current temperatures for each image can be found in the {{TAG\|OUTCAR}} files around the lines (all OUTCAR files will show the same information):

	parallel tempering new		parallel tempering new

	The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.3. If the acceptance ratio is too small, one usually needs to increase the number of images.		The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.2-0.3. If the acceptance ratio is too small, one usually needs to increase the number of images. However, too many images can also decrease the probability that all images visit all allowed temperatures.

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

Kresse: References added, equations added

2022-03-18T07:49:42Z

References added, equations added

← Older revision		Revision as of 07:49, 18 March 2022
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	VASP supports various modes where simultaneous calculations for different INCAR, KPOINTS, POTCAR, or POSCAR files are performed.		VASP supports various modes where simultaneous calculations for different INCAR, KPOINTS, POTCAR, or POSCAR files are performed.
	The parallel tempering mode is explained in this section, however, please read the section {{TAG\|IMAGES}} first.		The parallel tempering mode is explained in this section, however, please read the section {{TAG\|IMAGES}} first. Parallel tempering is also known as replica-exchange molecular dynamics.<ref name="sugi99"/>

	If the tags {{TAG\| IMAGES}}=nn and {{TAG\| LTEMPER}}=.TRUE. are set in the {{TAG\| INCAR}} file, VASP performs parallel tempering calculations. In this case, it is expedient to supply different {{TAG\| INCAR}} and {{TAG\| POSCAR}} files in each subdirectory 01, 02, 03, ..., nn. For each subdiretory a different simulation temperature should be supplied using the tags {{TAG\| TEBEG}} in the INCAR files 01/INCAR, 02/INCAR ... nn/INCAR.		If the tags {{TAG\| IMAGES}}=nn and {{TAG\| LTEMPER}}=.TRUE. are set in the {{TAG\| INCAR}} file, VASP performs parallel tempering calculations. In this case, it is expedient to supply different {{TAG\| INCAR}} and {{TAG\| POSCAR}} files in each subdirectory 01, 02, 03, ..., nn. For each subdiretory a different simulation temperature should be supplied using the tags {{TAG\| TEBEG}} in the INCAR files 01/INCAR, 02/INCAR ... nn/INCAR.

	In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every		In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every
	{{TAG\|NTEMPER}} MD steps. Information on the current temperatures for each image can be found in the {{TAG\|OUTCAR}} ~~file~~ around the lines		{{TAG\|NTEMPER}} MD steps, and accepted with a likelyhood of

			:<math> p = \min \left( 1, \frac{ \exp \left( -\frac{E_j}{kT_i} - \frac{E_i}{kT_j} \right) }{ \exp \left( -\frac{E_i}{kT_i} - \frac{E_j}{kT_j} \right) } \right) = \min \left( 1, e^{(E_i - E_j) \left( \frac{1}{kT_i} - \frac{1}{kT_j} \right)} \right) ,</math>


			where <math> E_i, E_j</math> and <math> T_i, T_j </math> are the energies and temperatures of the considered two replicas. Note that VASP swaps the temperatures and not the positions between images. This means that the temperatures in each subdirectory changes as the MD progresses. Information on the current temperatures for each image can be found in the {{TAG\|OUTCAR}} files around the lines (all OUTCAR files will show the same information):

	parallel tempering new		parallel tempering new

	The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.1. If the acceptance ratio is too small, one usually needs to increase the number of images.		The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.3. If the acceptance ratio is too small, one usually needs to increase the number of images.

	== Related Tags and Sections ==		== Related Tags and Sections ==
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	== References ==		== References ==
	<references>		<references>
			<ref name="sugi99">[http://dx.doi.org/10.1016/S0009-2614(99)01123-9 Y. Sugita and Y. Okamoto, Chemical Physics Letters. 314, 141 (1999).]</ref>
	</references>		</references>
	----		----

	[[Category:INCAR]][[Category:Parallel Tempering]]		[[Category:INCAR]][[Category:Parallel Tempering]]

Kresse at 08:30, 17 March 2022

2022-03-17T08:30:46Z

← Older revision

Revision as of 08:30, 17 March 2022

Kresse at 08:30, 17 March 2022

2022-03-17T08:30:46Z

← Older revision		Revision as of 08:30, 17 March 2022
Line 7:		Line 7:
	The parallel tempering mode is explained in this section, however, please read the section {{TAG\|IMAGES}} first.		The parallel tempering mode is explained in this section, however, please read the section {{TAG\|IMAGES}} first.

	If the tags {{TAG\| IMAGES}}=n and {{TAG\| LTEMPER}}=.TRUE. are set in the {{TAG\| INCAR}} file, VASP performs parallel tempering calculations. In this case, it is expedient to supply different {{TAG\| INCAR}} and {{TAG\| POSCAR}} files in each subdirectory 01, 02, 03... ~~IMAGES~~. For each subdiretory a different simulation temperature should be supplied using the tags {{TAG\| TEBEG}}.		If the tags {{TAG\| IMAGES}}=nn and {{TAG\| LTEMPER}}=.TRUE. are set in the {{TAG\| INCAR}} file, VASP performs parallel tempering calculations. In this case, it is expedient to supply different {{TAG\| INCAR}} and {{TAG\| POSCAR}} files in each subdirectory 01, 02, 03, ..., nn. For each subdiretory a different simulation temperature should be supplied using the tags {{TAG\| TEBEG}} in the INCAR files 01/INCAR, 02/INCAR ... nn/INCAR.

	In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every		In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every
	{{TAG\|NTEMPER}} MD steps. Information on the current temperatures for each image can be found in the {{TAG\|OUTCAR}} file around the lines		{{TAG\|NTEMPER}} MD steps. Information on the current temperatures for each image can be found in the {{TAG\|OUTCAR}} file around the lines

	parallel tempering		parallel tempering new

	The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should ~~most likely approach at least~~ 0.1. If ~~this~~ is ~~not the case~~, one needs to increase the number of images.		The average acceptance ratios are also written to the {{TAG\|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should not fall much below 0.1. If the acceptance ratio is too small, one usually needs to increase the number of images.

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

Kresse: Created page with "{{TAGDEF|LTEMPER|[logical]|.FALSE.}} Description: {{TAG|LTEMPER}} specified whether parallel tempering is used. The flag must be used in combination with {{TAG|IMAGES}}. --..."

2022-03-17T08:08:56Z

Created page with "{{TAGDEF|LTEMPER|[logical]|.FALSE.}} Description: {{TAG|LTEMPER}} specified whether parallel tempering is used. The flag must be used in combination with {{TAG|IMAGES}}. --..."

New page

{{TAGDEF|LTEMPER|[logical]|.FALSE.}}

Description: {{TAG|LTEMPER}} specified whether parallel tempering is used. The flag must be used in combination with {{TAG|IMAGES}}.

----
VASP supports various modes where simultaneous calculations for different INCAR, KPOINTS, POTCAR, or POSCAR files are performed.
The parallel tempering mode is explained in this section, however, please read the section {{TAG|IMAGES}} first.

If the tags {{TAG| IMAGES}}=n and {{TAG| LTEMPER}}=.TRUE. are set in the {{TAG| INCAR}} file, VASP performs parallel tempering calculations. In this case, it is expedient to supply different {{TAG| INCAR}} and {{TAG| POSCAR}} files in each subdirectory 01, 02, 03... IMAGES. For each subdiretory a different simulation temperature should be supplied using the tags {{TAG| TEBEG}}.

In the course of the simulations, VASP will attempt to swap the temperatures between the images. Swapping attempts are made every
{{TAG|NTEMPER}} MD steps. Information on the current temperatures for each image can be found in the {{TAG|OUTCAR}} file around the lines

parallel tempering

The average acceptance ratios are also written to the {{TAG|OUTCAR}} file. For efficient parallel tempering the acceptance ratio should most likely approach at least 0.1. If this is not the case, one needs to increase the number of images.

== Related Tags and Sections ==
{{TAG|IMAGES}},
{{TAG|NTEMPER}}

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

== References ==
<references>
</references>
----

[[Category:INCAR]][[Category:Parallel Tempering]]