LHARTREE: Difference between revisions

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{{TAG|LADDER}} is used together with {{TAG|LHARTREE}}. If {{TAG|LADDER}}=''.FALSE.'', the ladder diagrams (i.e. the exchange terms related to <math>W</math> or the screened exchange) are not included.
{{TAG|LADDER}} is used together with {{TAG|LHARTREE}}. If {{TAG|LADDER}}=''.FALSE.'', the ladder diagrams, i.e., the exchange terms related to <math>W</math> or the screened exchange, are not included.
If {{TAG|LHARTREE}}=''.FALSE.'', the Hartree diagrams or bubble diagrams are not included. The following table summarizes all possible combinations:
If {{TAG|LHARTREE}}=''.FALSE.'', the Hartree diagrams or bubble diagrams are not included. The following table summarizes all possible combinations:


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The last combination can be useful for sanity checks: the results must be identical to the results obtained using
The last combination can be useful for sanity checks: the results must be identical to the results obtained using
{{TAG|LOPTICS}}=''.TRUE.'' in the preceding calculations. If this is not the case, it usually implies that the one-electron
{{TAG|LOPTICS}}=''.TRUE.'' in the preceding calculations. If this is not the case, it usually implies that the one-electron
energies have been updated in the {{TAG|WAVECAR}} file, or that the  {{TAG|WAVEDER}} file is not properly set up. The end of {{TAG|BSE}} explains how to recalculate
energies have been updated in the {{TAG|WAVECAR}} file, or that the  {{TAG|WAVEDER}} file is not properly set up. The end of [[BSE calculations|BSE]] explains how to recalculate the {{TAG|WAVEDER}} file from an existing {{TAG|WAVECAR}} file.
the {{TAG|WAVEDER}} file from an existing {{TAG|WAVECAR}} file.


== Related Tags and Sections ==
== Related tags and articles ==
{{TAG|LADDER}},
{{TAG|LADDER}},
{{TAG|LOPTICS}},
{{TAG|LOPTICS}},
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[[Category:INCAR]][[Category:Many-Body Perturbation Theory]][[Category:BSE]]
[[Category:INCAR tag]][[Category:Many-body perturbation theory]][[Category:Bethe-Salpeter equations]]

Latest revision as of 08:30, 19 July 2022

LHARTREE = [logical]
Default: LHARTREE = .TRUE. 

Description: Controls whether the bubble diagrams are included in the BSE calculation.


LADDER is used together with LHARTREE. If LADDER=.FALSE., the ladder diagrams, i.e., the exchange terms related to or the screened exchange, are not included. If LHARTREE=.FALSE., the Hartree diagrams or bubble diagrams are not included. The following table summarizes all possible combinations:

LHARTREE LADDER
.TRUE. .TRUE. full BSE
.FALSE. .TRUE. only excitonic effects (ladders)
.TRUE. .FALSE. random phase approximation (rings = bubbles only)
.FALSE. .FALSE. independent particle picture

The last combination can be useful for sanity checks: the results must be identical to the results obtained using LOPTICS=.TRUE. in the preceding calculations. If this is not the case, it usually implies that the one-electron energies have been updated in the WAVECAR file, or that the WAVEDER file is not properly set up. The end of BSE explains how to recalculate the WAVEDER file from an existing WAVECAR file.

Related tags and articles

LADDER, LOPTICS, BSE calculations

Examples that use this tag