IWAVPR: Difference between revisions

Latest revision as of 10:56, 14 February 2025

IWAVPR = 0 | 1 | 2 | 3 | 10 | 11 | 12 | 13

Default: IWAVPR	= 12	if IBRION=0 (MD) and 11 (relaxation, on-the-fly machine learning MD)
	= 0	else (static calculation)

Description: IWAVPR determines how orbitals and/or charge densities are extrapolated from one ionic configuration to the next configuration.

For IWAVPR<10, the file TMPCAR is used to store old orbitals that are required for the prediction. This setting is depreciated, and not supported by the MPI version. The recommended settings are IWAVPR>10. In this case, the prediction is performed without an external file TMPCAR (i.e. all required arrays are stored in the main memory).

The following options are available for IWAVPR:

IWAVPR=0 no extrapolation, usually not preferable for first-principles molecular dynamics simulations or relaxations of the ions into the groundstate.
IWAVPR=1|11 Simple extrapolation of the charge density using atomic charge densities (eq. (9.8) in thesis G. Kresse). This switch is convenient for geometry optimizations (ionic relaxation and volume/cell shape with the conjugate gradient or Quasi-Newton methods, i.e. IBRION=1,2,3 etc.)
IWAVPR=2|12 A second-order extrapolation for the orbitals and the charge density (eq. (9.9) in thesis G. Kresse) is performed. This results in superior performance for first-principles molecular-dynamics simulations. It might cause instabilities during on-the-fly learning, so the default is 11 in this case.

IWAVPR=3|13 In this case a second-order extrapolation for the orbitals, and a simple extrapolation of the charge density using atomic charge densities is done. This is a mixture between IWAVPR=1 and 2, however, it is usually worse than IWAVPR=2.

Mind: We don't encourage this setting.

@@ Line 1: / Line 1: @@
 {{TAGDEF|IWAVPR|0 {{!}} 1 {{!}} 2 {{!}} 3 {{!}} 10 {{!}} 11 {{!}} 12 {{!}} 13}}
-{{DEF|IWAVPR|2|if {{TAG|IBRION}}{{=}}0 and 1,2 (relaxation)|0|else (static calculation)}}
+{{DEF|IWAVPR|12|if {{TAG|IBRION}}{{=}}0 (MD) and 11 (relaxation, on-the-fly machine learning MD)|0|else (static calculation)}}
-{\tt IWAVPR}= {\tt 0 | 1 | 2 | 3 | 10 | 11 | 12 | 13}
+Description: {{TAG|IWAVPR}} determines how orbitals and/or charge densities
+are extrapolated from one ionic configuration to the next configuration.
+----
+For {{TAG|IWAVPR}}<10, the file {{TAG|TMPCAR}} is used to store old orbitals that
+are required for the prediction. This setting is depreciated, and not supported by the MPI version.
+The recommended settings are {{TAG|IWAVPR}}>10. In this case, the prediction is
+performed without an external file {{TAG|TMPCAR}} (i.e. all required arrays
+are stored in the main memory).
-\begin{tabular} {rl}
+The following options are available for {{TAG|IWAVPR}}:
-Default: \\
+*{{TAG|IWAVPR}}=0 no extrapolation, usually not preferable for first-principles molecular dynamics simulations or relaxations of the ions into the groundstate.
-{\tt IWAVPR}=2 & if {\tt IBRION}=0 (MD) and 1,2 (relaxation) \\
+*{{TAG|IWAVPR}}=1|11 Simple extrapolation of the charge density using atomic charge densities (eq. (9.8) in thesis G. Kresse). This switch is convenient for geometry optimizations (ionic relaxation and volume/cell shape with the conjugate gradient or Quasi-Newton methods, i.e. {{TAG|IBRION}}=1,2,3 etc.)
-            =0 & else (static calculation) \\
+*{{TAG|IWAVPR}}=2|12 A second-order extrapolation for the orbitals and the charge density (eq. (9.9) in thesis G. Kresse) is performed. This results in superior performance for first-principles molecular-dynamics simulations. It might cause instabilities during on-the-fly learning, so the default is 11 in this case.
-\end{tabular}
-\vspace{5mm}
-\noindent
+<!--However, the following warning may occur: <code>Information: wavefunction orthogonal band xxx..</code>. This is a sign of band crossing and -->
-{\tt IWAVPR} determines how orbitals and/or charge density
+*{{TAG|IWAVPR}}=3|13 In this case a second-order extrapolation for the orbitals, and a simple extrapolation of the charge density using atomic charge densities is done. This is a mixture between {{TAG|IWAVPR}}=1 and 2, however, it is usually worse than {{TAG|IWAVPR}}=2.
-are extrapolated from one ionic configuration to the next configuration.
+:Mind: We don't encourage this setting.
-Usually the file TMPCAR \index{FILES!T!TMPCAR|textit} is used to store
-old orbitals, which
-are required for the prediction.
-If {\tt IWAVPR} is larger than 10, the prediction is
-done without an external file TMPCAR (i.e. all required arrays
-are stored in main  memory, this option works from version VASP.4.1).
-If the {\tt IWAVPR} is set to 10, the reader will set it to the
-following default values:
-\begin{tabular} {ll}
+== Related tags and articles ==
-{\tt IWAVPRE}=12 & if {\tt IBRION}=0 (MD) \\
+{{TAG|IBRION}}
-{\tt IWAVPRE}=11 & if {\tt IBRION}=1,2 (relaxation) \\
-\end{tabular}
-\vspace{5mm}
-\begin{itemize}
+{{sc|IWAVPR|Examples|Examples that use this tag}}
-\item[0]
+----
-no extrapolation, usually less preferable if you want to do an
-ab initio MD or a relaxation of the ions into the instantaneous groundstate.
-\item[1,11]
-Simple extrapolation of the charge density using atomic charge densities is done
-(eq. (9.8) in thesis G. Kresse).
-This switch is convenient for all kind of geometry optimizations (ionic relaxation
-and volume/cell shape with conjugate gradient or Quasi-Newton methods,
-i.e. {\tt IBRION}=1,2) \index{INCAR!I!IBRION|textit}
-\item[2,12]
-A second order extrapolation for the orbitals and
-the charge density is done (eq. (9.9) in thesis G. Kresse).
-A must for ab-initio  MD-runs.
-\item[3,13]
-In this case a second order extrapolation for the orbitals, and
-a  simple  extrapolation of the charge density using atomic charge densities is done.
-This is obviously a mixture between {\tt IWAVPR}=1 and 2, however, it is usually worse
-than {\tt IWAVPR}=2.
-{\em Mind:} We don't  encourage this  setting.
+[[Category:INCAR tag]][[Category:Ionic minimization]][[Category:Molecular dynamics]]