LSPECTRALGW: Difference between revisions

Revision as of 16:12, 15 September 2017

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 $\Sigma(\omega)= G W$ is calculated from the imaginary part of screened potential $W(\omega)$ by shifting the poles of $W$ by $\pm \epsilon$ , where $\epsilon$ are the poles of the Green's function $G$ . 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 Sections

LSPECTRAL

Examples that use this tag

Contents

@@ Line 8: / Line 8: @@
 Generally, {{TAG|LSPECTRALGW}} affects the compute time very little. QP energies also hardly
 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,
 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.
+range of values (0.5<Z<0.9).