LSPECTRALGW: Difference between revisions

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{{TAGDEF|LSPECTRALGW|.FALSE. {{!}} .TRUE.}}
{{TAGDEF|LSPECTRALGW|.FALSE. {{!}} .TRUE.|.FALSE.}}
{{DEF|LSPECTRALGW|.FALSE.}}


Description: {{TAG|LSPECTRALGW}} specifies to use the spectral method for calculating the self-energy.
Description: {{TAG|LSPECTRALGW}} specifies to use the spectral method for calculating the self-energy.
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Generally, {{TAG|LSPECTRALGW}} affects the compute time very little. QP energies also hardly
Generally, {{TAG|LSPECTRALGW}} affects the compute time very little. QP energies also hardly
change when {{TAG|LSPECTRALGW}}  is modified.
change when {{TAG|LSPECTRALGW}}  is modified.
However, {{TAG|LSPECTRALGW}} = .TRUE. is usually is slightly more robust,
However, {{TAG|LSPECTRALGW}} = .TRUE. is usually slightly more robust,
and should be selected for molecules and other systems with flat bands.   
and should be selected for molecules and other systems with flat dispersion-less bands.   
One the other hand, {{TAG|LSPECTRALGW}} = .TRUE. seems to converge slightly slower,  
One the other hand, {{TAG|LSPECTRALGW}} = .TRUE. seems to converge slightly slower,  
as the complex shift {{TAG|CSHIFT}} is decreased.
as the complex shift {{TAG|CSHIFT}} is decreased. Set this flag, if the QP energies
show erratic behavior, for instance, if QP energies or Z-factors are not in the expected
range of values (0.5<Z<0.9).




== Related Tags and Sections ==
== Related tags and articles ==
{{TAG|LSPECTRAL}}
{{TAG|LSPECTRAL}}


== Example Calculations using this Tag ==
{{sc|LSPECTRALGW|Examples|Examples that use this tag}}
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[[The_VASP_Manual|Contents]]


[[Category:INCAR]] [[Category:GW]]
[[Category:INCAR tag]][[Category:Many-body perturbation theory]][[Category:GW]]

Latest revision as of 10:12, 19 July 2022

LSPECTRALGW = .FALSE. | .TRUE.
Default: LSPECTRALGW = .FALSE. 

Description: LSPECTRALGW specifies to use the spectral method for calculating the self-energy.


If LSPECTRALGW = .TRUE. is set, the imaginary part of the self-energy is calculated from the imaginary part of screened potential by shifting the poles of by , where are the poles of the Green's function . Generally, LSPECTRALGW affects the compute time very little. QP energies also hardly change when LSPECTRALGW is modified. However, LSPECTRALGW = .TRUE. is usually slightly more robust, and should be selected for molecules and other systems with flat dispersion-less bands. One the other hand, LSPECTRALGW = .TRUE. seems to converge slightly slower, as the complex shift CSHIFT is decreased. Set this flag, if the QP energies show erratic behavior, for instance, if QP energies or Z-factors are not in the expected range of values (0.5<Z<0.9).


Related tags and articles

LSPECTRAL

Examples that use this tag