NBLOCK: Difference between revisions

Latest revision as of 13:32, 20 March 2024

NBLOCK = [integer]
Default: NBLOCK = 1

Description: After NBLOCK ionic steps the pair-correlation function and the DOS are calculated and the ionic configuration is written to the XDATCAR-file.

It is recommended to leave NBLOCK to 1, since the computational overhead to determine the DOS and pair correlation function is minimal. Only for molecular dynamics simulations with many 1000 steps or when using machine-learned force fields, it might be expedient to increase NBLOCK to say 10 or even 100, to avoid large XDATCAR-files and the evaluation of the pair correlation function at every step.

Tip: If machine-learned force fields are used in prediction-only mode (ML_MODE = predict) prefer to use the ML_OUTBLOCK tag instead of NBLOCK to control the output frequency.

In addition

NBLOCK controls how often the kinetic energy is scaled if SMASS = -1.

After KBLOCK * NBLOCK ionic steps the averaged pair correlation function and DOS are written to the files PCDAT and DOSCAR. The internal accumulators are reset, and after another KBLOCK * NBLOCK steps the new averaged quantities are written out.

Warning: The product of KBLOCK and NBLOCK should not be larger than the number of steps NSW. If KBLOCK * NBLOCK > NSW before starting the main ion loop then KBLOCK is automatically reset to 1. Next, if the same conditions is still true, NBLOCK is reset to NSW. Also, mind that NBLOCK will be at minimum ML_OUTBLOCK in MLFF prediction-only MD runs.

@@ Line 1: / Line 1: @@
 {{TAGDEF|NBLOCK|[integer]|1}}
-Description: after {{TAG|NBLOCK}}  ionic steps the pair correlation function and the DOS are calculated
+Description: After {{TAG|NBLOCK}} ionic steps the pair-correlation function and the DOS are calculated
-and the ionic configuration is written to the {{FILE|XDATCAR}}-file. It is recommended to leave  {{TAG|NBLOCK}} to 1, since the computational overhead to determine the DOS and pair correlation function is minimal. Only for  molecular dynamics simulations with many 1000 steps, it might be expedient to increase {{TAG|NBLOCK}} to say 10, to avoid large {{FILE|XDATCAR}}-files.
+and the ionic configuration is written to the {{FILE|XDATCAR}}-file.
 ----
+It is recommended to leave  {{TAG|NBLOCK}} to 1, since the computational overhead to determine the DOS and pair correlation function is minimal. Only for  molecular dynamics simulations with many 1000 steps or when using machine-learned force fields, it might be expedient to increase {{TAG|NBLOCK}} to say 10 or even 100, to avoid large {{FILE|XDATCAR}}-files and the evaluation of the pair correlation function at every step. {{NB|tip|If machine-learned force fields are used in prediction-only mode ({{TAGO|ML_MODE|predict}}) prefer to use the {{TAG|ML_OUTBLOCK}} tag instead of {{TAG|NBLOCK}} to control the output frequency.}}
 In addition
-*{{TAG|NBLOCK}} controls how often the kinetic energy is scaled if {{TAG|SMASS}}=-1.
+*{{TAG|NBLOCK}} controls how often the kinetic energy is scaled if {{TAGO|SMASS|-1}}.
-*After {{TAG|KBLOCK}}*{{TAG|NBLOCK}} main loops the averaged pair correlation function and DOS are written to the files {{FILE|PCDAT}}  and {{FILE|DOSCAR}}
-''Mind'': The CPU costs for these tasks are quite small, so use {{TAG|NBLOCK}}=1.
+*After <code>{{TAG|KBLOCK}} * {{TAG|NBLOCK}}</code> ionic steps the averaged pair correlation function and DOS are written to the files {{FILE|PCDAT}}  and {{FILE|DOSCAR}}. The internal accumulators are reset, and after another <code>{{TAG|KBLOCK}} * {{TAG|NBLOCK}}</code> steps the new averaged quantities are written out. {{NB|warning|The product of {{TAG|KBLOCK}} and {{TAG|NBLOCK}} should not be larger than the number of steps {{TAG|NSW}}. If <code>{{TAG|KBLOCK}} * {{TAG|NBLOCK}} > {{TAG|NSW}}</code> before starting the main ion loop then {{TAG|KBLOCK}} is automatically reset to 1. Next, if the same conditions is still true, {{TAG|NBLOCK}} is reset to {{TAG|NSW}}. Also, mind that {{TAG|NBLOCK}} will be at minimum {{TAG|ML_OUTBLOCK}} in MLFF prediction-only MD runs.}}
-== Related Tags and Sections ==
+== Related tags and articles ==
-{{TAG|KBLOCK}}
+[[PCDAT]], [[DOSCAR]], [[XDATCAR]], {{TAG|KBLOCK}}, {{TAG|ML_OUTBLOCK}}
 {{sc|NBLOCK|Examples|Examples that use this tag}}
 ----
-[[The_VASP_Manual|Contents]]
-[[Category:INCAR]][[Category:Molecular Dynamics]]
+[[Category:INCAR tag]][[Category:Molecular dynamics]][[Category:Performance]]