View source for Restart and output files cheat sheet

VASP can continue a calculation from the converged results of a previous run instead of restarting the electronic minimization from scratch. The wavefunctions are reused through {{TAG|ISTART}} and the charge density through {{TAG|ICHARG}}; some methods additionally need the kinetic energy density or the local potential. The files that store these quantities are the ''restart files''.

The restart files are {{FILE|WAVECAR}} (wavefunctions), {{FILE|CHGCAR}} (charge density together with the PAW one-center occupancies), {{FILE|TAUCAR}} (kinetic energy density, for meta-GGA functionals), and {{FILE|POT}} (local potential, for OEP calculations). Alternatively, these quantities are written to the single HDF5 file {{FILE|vaspwave.h5}}. The restart files differ from analysis and visualization output such as {{FILE|CHG}}, {{FILE|LOCPOT}}, {{FILE|DOSCAR}}, or {{FILE|vasprun.xml}}: the latter store derived or reduced quantities (for example, {{FILE|CHG}} omits the PAW one-center occupancies) and are not read back to continue a calculation.

Which restart files are written, and whether in the legacy format or in {{FILE|vaspwave.h5}}, is controlled by {{TAG|LWAVE}}, {{TAG|LCHARG}}, {{TAG|LTAU}}, {{TAG|LVTOT}}, {{TAG|LH5}}, and {{TAG|LCHARGH5}}.

== How the tags interact ==

{{TAG|LWAVE}}, {{TAG|LCHARG}}, {{TAG|LTAU}}, and {{TAG|LVTOT}} decide '''whether''' the wavefunctions, the charge density, the kinetic energy density, and the local potential are written. {{TAG|LH5}} decides the '''format''': the legacy files for {{TAG|LH5|.FALSE.}}, or {{FILE|vaspwave.h5}} for {{TAG|LH5|.TRUE.}}, which suppresses the legacy files entirely. {{TAG|LCHARGH5}} is the exception: rather than switching the format, it writes the charge density to {{FILE|vaspwave.h5}} ''in addition'', so that the density is available for plotting with {{py4vasp}} while the restart information is still written to the legacy files.

The files are written according to the following rules:
* {{FILE|WAVECAR}} &mdash; {{TAG|LWAVE|.TRUE.}} and {{TAG|LH5|.FALSE.}}; the {{FILE|vaspwave.h5}} group <code>/wave</code> &mdash; {{TAG|LWAVE|.TRUE.}} and {{TAG|LH5|.TRUE.}}
* {{FILE|CHGCAR}} &mdash; {{TAG|LCHARG|.TRUE.}} and {{TAG|LH5|.FALSE.}}; the {{FILE|vaspwave.h5}} group <code>/charge</code> &mdash; {{TAG|LCHARGH5|.TRUE.}}
* {{FILE|TAUCAR}} &mdash; like {{FILE|CHGCAR}}, but additionally requires {{TAG|LTAU|.TRUE.}}; the {{FILE|vaspwave.h5}} group <code>/kinetic_energy_density</code> follows the <code>/charge</code> rule. {{TAG|LTAU}} defaults to {{TAG|LTAU|.TRUE.}} for meta-GGA functionals.
* {{FILE|POT}} &mdash; {{TAG|LVTOT|.TRUE.}} and {{TAG|LH5|.FALSE.}}; the {{FILE|vaspwave.h5}} group <code>/potential</code> requires {{TAG|LVTOT|.TRUE.}} and {{TAG|LH5|.TRUE.}}. Only OEP and hybrid-functional OEP calculations write {{FILE|POT}}.
{{NB|mind|{{FILE|CHG}} is written together with {{FILE|CHGCAR}} under the same condition, but it omits the PAW one-center occupancies. Like {{FILE|LOCPOT}}, it is an analysis file and not a restart file.}}

=== Defaults ===

The defaults of {{TAG|LWAVE}}, {{TAG|LCHARG}}, {{TAG|LH5}}, and {{TAG|LVTOT}} are fixed and do not depend on the other tags:
* {{TAG|LWAVE|.TRUE.}}
* {{TAG|LCHARG|.TRUE.}}
* {{TAG|LH5|.FALSE.}}
* {{TAG|LVTOT|.FALSE.}}

{{TAG|LTAU}} defaults to {{TAG|LTAU|.TRUE.}} for meta-GGA functionals that need the kinetic energy density, and to {{TAG|LTAU|.FALSE.}} otherwise. {{TAG|LCHARGH5}} also has no fixed default: when it is not set, its value is {{TAG|LH5}} <code>.AND.</code> {{TAG|LCHARG}}. As a result, switching to HDF5 output with {{TAG|LH5|.TRUE.}} writes the charge density to {{FILE|vaspwave.h5}} automatically (as long as {{TAG|LCHARG|.TRUE.}}), while an explicit {{TAG|LCHARGH5|.FALSE.}} suppresses it.
{{NB|tip|To plot the charge density with {{py4vasp}} while still writing restart information to the legacy {{FILE|WAVECAR}}, set {{TAG|LCHARGH5|.TRUE.}} together with {{TAG|LH5|.FALSE.}}.}}

== Overview table ==

The table covers the wavefunctions and the charge density for every combination of effective (i.e., after applying the defaults) tag values. ✓ marks a written file, &mdash; a file that is not written. The highlighted row is the default configuration. The kinetic energy density ({{FILE|TAUCAR}}) and the OEP local potential ({{FILE|POT}}) follow the same pattern as the charge density, additionally gated by {{TAG|LTAU}} and {{TAG|LVTOT}}.

{| class="wikitable" style="text-align:center;"
|+ Restart files written for each effective tag combination (wavefunctions and charge density)
! {{TAG|LWAVE}} !! {{TAG|LCHARG}} !! {{TAG|LH5}} !! {{TAG|LCHARGH5}} !! {{FILE|WAVECAR}} !! {{FILE|CHGCAR}} !! {{FILE|vaspwave.h5}} /wave !! {{FILE|vaspwave.h5}} /charge
|- style="background:#eaffea;"
| .TRUE. || .TRUE. || .FALSE. || .FALSE. || ✓ || ✓ || — || —
|-
| .TRUE. || .TRUE. || .FALSE. || .TRUE. || ✓ || ✓ || — || ✓
|-
| .TRUE. || .FALSE. || .FALSE. || .FALSE. || ✓ || — || — || —
|-
| .TRUE. || .FALSE. || .FALSE. || .TRUE. || ✓ || — || — || ✓
|-
| .FALSE. || .TRUE. || .FALSE. || .FALSE. || — || ✓ || — || —
|-
| .FALSE. || .TRUE. || .FALSE. || .TRUE. || — || ✓ || — || ✓
|-
| .FALSE. || .FALSE. || .FALSE. || .FALSE. || — || — || — || —
|-
| .FALSE. || .FALSE. || .FALSE. || .TRUE. || — || — || — || ✓
|-
| .TRUE. || .TRUE. || .TRUE. || .FALSE. || — || — || ✓ || —
|-
| .TRUE. || .TRUE. || .TRUE. || .TRUE. || — || — || ✓ || ✓
|-
| .TRUE. || .FALSE. || .TRUE. || .FALSE. || — || — || ✓ || —
|-
| .TRUE. || .FALSE. || .TRUE. || .TRUE. || — || — || ✓ || ✓
|-
| .FALSE. || .TRUE. || .TRUE. || .FALSE. || — || — || — || —
|-
| .FALSE. || .TRUE. || .TRUE. || .TRUE. || — || — || — || ✓
|-
| .FALSE. || .FALSE. || .TRUE. || .FALSE. || — || — || — || —
|-
| .FALSE. || .FALSE. || .TRUE. || .TRUE. || — || — || — || ✓
|}
{{NB|mind|The tag {{TAG|LWAVEH5}} has no effect in current versions of VASP and is ignored. Use {{TAG|LH5}} to redirect the wavefunctions to {{FILE|vaspwave.h5}}.}}
{{NB|mind|Reading the charge density back from {{FILE|vaspwave.h5}} is not yet implemented. A fixed-density restart ({{TAG|ICHARG|11}}) cannot use a {{FILE|vaspwave.h5}} that was written with {{TAG|LH5|.TRUE.}}; write the {{FILE|CHGCAR}} for such restarts. See [[Known issues#KnownIssue73]].}}
{{NB|mind|This page describes VASP 6.5 and later. HDF5 output ({{FILE|vaspwave.h5}}) is available as of VASP 6.0, and additional datasets are written as of VASP 6.6.0. In VASP 6.0 to 6.4.2 the default of {{TAG|LCHARG}} was <code>.NOT.</code>{{TAG|LH5}}, and some combinations with {{TAG|LH5|.TRUE.}} still wrote the legacy {{FILE|CHGCAR}}.}}

== Related tags and articles ==

Files: {{FILE|WAVECAR}}, {{FILE|CHGCAR}}, {{FILE|CHG}}, {{FILE|TAUCAR}}, {{FILE|POT}}, {{FILE|LOCPOT}}, {{FILE|vaspwave.h5}}

Tags: {{TAG|LWAVE}}, {{TAG|LCHARG}}, {{TAG|LCHARGH5}}, {{TAG|LTAU}}, {{TAG|LVTOT}}, {{TAG|LH5}}, {{TAG|ISTART}}, {{TAG|ICHARG}}

== References ==
<references/>

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