Slow-growth approach calculations: Difference between revisions
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VASP can handle multiple (even redundant) constraints. Note, however, that a too large number of constraints can cause problems with the stability of the [[#SHAKE|SHAKE algorithm]]. In problematic cases, it is recommended to use a looser convergence criterion (see {{TAG|SHAKETOL}}) and to allow a larger number of iterations (see {{TAG|SHAKEMAXITER}}) in the [[#SHAKE|SHAKE algorithm]]. Hard constraints may also be used in [[ | VASP can handle multiple (even redundant) constraints. Note, however, that a too large number of constraints can cause problems with the stability of the [[#SHAKE|SHAKE algorithm]]. In problematic cases, it is recommended to use a looser convergence criterion (see {{TAG|SHAKETOL}}) and to allow a larger number of iterations (see {{TAG|SHAKEMAXITER}}) in the [[#SHAKE|SHAKE algorithm]]. Hard constraints may also be used in [[Metadynamics|metadynamics simulations]] (see {{TAG|MDALGO}}=11 {{!}} 21). Information about the constraints is written onto the {{FILE|REPORT}}-file: check the lines following the string: <tt>Const_coord</tt> | ||
== Related tags and articles == | == Related tags and articles == | ||
{{FILE|ICONST}}, {{TAG|INCREM}}, {{TAG|SHAKEMAXITER}}, {{TAG|SHAKETOL}}, {{TAG|SHAKETOLSOFT}}, {{TAG|LBLUEOUT}}, {{FILE|REPORT}} | {{FILE|ICONST}}, {{TAG|INCREM}}, {{TAG|SHAKEMAXITER}}, {{TAG|SHAKETOL}}, {{TAG|SHAKETOLSOFT}}, {{TAG|LBLUEOUT}}, {{FILE|REPORT}} | ||
[[Slow-growth approach]] | |||
[[Category:Advanced molecular-dynamics sampling]][[Category:Howto]] | [[Category:Advanced molecular-dynamics sampling]][[Category:Howto]] | ||
Latest revision as of 15:02, 28 May 2026
Anderson thermostat
- For a slow-growth simulation, one has to perform a calcualtion very similar to Constrained molecular dynamics but additionally the transformation velocity-related INCREM-tag for each geometric parameter with STATUS=0 has to be specified. For a slow-growth approach run with Andersen thermostat, one has to:
- Set the standard MD-related tags: IBRION=0, TEBEG, POTIM, and NSW
- Set MDALGO=1, and choose an appropriate setting for ANDERSEN_PROB
- Define geometric constraints in the ICONST file, and set the STATUS parameter for the constrained coordinates to 0
- When the free-energy gradient is to be computed, set LBLUEOUT=.TRUE.
- Specify the transformation velocity-related INCREM-tag for each geometric parameter with STATUS=0.
Nose-Hoover thermostat
- For a slow-growth approach run with Nose-Hoover thermostat, one has to:
- Set the standard MD-related tags: IBRION=0, TEBEG, POTIM, and NSW
- Set MDALGO=2, and choose an appropriate setting for SMASS
- Define geometric constraints in the ICONST-file, and set the STATUS parameter for the constrained coordinates to 0
- When the free-energy gradient is to be computed, set LBLUEOUT=.TRUE.
- Specify the transformation velocity-related INCREM-tag for each geometric parameter with STATUS=0
VASP can handle multiple (even redundant) constraints. Note, however, that a too large number of constraints can cause problems with the stability of the SHAKE algorithm. In problematic cases, it is recommended to use a looser convergence criterion (see SHAKETOL) and to allow a larger number of iterations (see SHAKEMAXITER) in the SHAKE algorithm. Hard constraints may also be used in metadynamics simulations (see MDALGO=11 | 21). Information about the constraints is written onto the REPORT-file: check the lines following the string: Const_coord
Related tags and articles
ICONST, INCREM, SHAKEMAXITER, SHAKETOL, SHAKETOLSOFT, LBLUEOUT, REPORT