NTEMPER: Difference between revisions

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{{TAG|NTEMPER}} must be a positive integer. Swaps are on average attempted after {{TAG|NTEMPER}} molecular dynamics steps.
{{TAG|NTEMPER}} must be a positive integer or zero. Swaps are on average attempted after {{TAG|NTEMPER}} molecular dynamics steps.
Specifically, a random number <math> r </math> between [0,1[ is drawn. The next temperature swaps are attempted after  
Specifically, a random number <math> r </math> between [0,1[ is drawn. The next temperature swaps are attempted after  
{{TAG|NTEMPER}} <math> \times  2~ r -1 </math>  steps. Obviously, for {{TAG|NTEMPER}}=1 swaps are attempted at every MD step. In the present code version, temperature swaps are alternatively performed between images 1,2 and 3,4 and 5,6 etc. Upon the next swap attempts, the swaps are attempted between imaged 2,3 and 4,5 and 6,7 etc.
{{TAG|NTEMPER}} <math> \times  2~ r -1 </math>  steps. Obviously, for {{TAG|NTEMPER}}=1 swaps are attempted at every MD step. In the present code version, temperature swaps are alternatively performed between images 1,2 and 3,4 and 5,6 etc., or upon the next swap between images 2,3 and 4,5 and 6,7 etc.
This implies that many swaps are attempted at the same time.
This implies that many swaps are attempted at the same time.


Furthermore, for {{TAG|NTEMPER}}=0 no temperature swaps are attempted. This can be useful to perform many independent calculations in the directories 01, 02, 03, ... .
Furthermore, no temperature swapping is attempted for {{TAG|NTEMPER}}=0. This allows many independent calculations to be performed in directories 01, 02, 03, ... which can be useful when performing many similar calculations for small systems or using machine-learned force fields on many-core machines (strong scaling is sometimes not particularly good for small systems).
   
   
A final note is in place. The tag {{TAG|NTEMPER}}  must be set in the {{TAG|INCAR}} files of the subdirectories 01, 02, 03, and {{TAG|NTEMPER}} must be identical in all
A final note is in place. The tag {{TAG|NTEMPER}}  must be set in the {{TAG|INCAR}} files of the subdirectories 01, 02, 03, and {{TAG|NTEMPER}} must be identical in all

Revision as of 16:46, 12 March 2024

NTEMPER = [integer]
Default: NTEMPER = 200 

Description: NTEMPER specifies how often temperature swaps are attempted during parallel tempering. The flag must be used in combination with IMAGES and LTEMPER.


NTEMPER must be a positive integer or zero. Swaps are on average attempted after NTEMPER molecular dynamics steps. Specifically, a random number between [0,1[ is drawn. The next temperature swaps are attempted after NTEMPER steps. Obviously, for NTEMPER=1 swaps are attempted at every MD step. In the present code version, temperature swaps are alternatively performed between images 1,2 and 3,4 and 5,6 etc., or upon the next swap between images 2,3 and 4,5 and 6,7 etc. This implies that many swaps are attempted at the same time.

Furthermore, no temperature swapping is attempted for NTEMPER=0. This allows many independent calculations to be performed in directories 01, 02, 03, ... which can be useful when performing many similar calculations for small systems or using machine-learned force fields on many-core machines (strong scaling is sometimes not particularly good for small systems).

A final note is in place. The tag NTEMPER must be set in the INCAR files of the subdirectories 01, 02, 03, and NTEMPER must be identical in all subdirectories. Failure to observe this rule can lead to unexpected behavior.

Related tags and articles

IMAGES, LTEMPER

Examples that use this tag

References