SCREENING_IN_W

Screening \(\epsilon\) applied to \(W(\omega=0)=\epsilon^{-1}(\omega=0) v \) in the BSE calculation. Besides default BSE, i.e. \(W_0\) (screening with DFT energies), a fixed \(\alpha = \epsilon^{-1}(\omega)\) can be applied, which is similar to the mixing parameter for hybrid functionals in LR-TDDFT. In addition, the keywords TDHF (no screening - \(\alpha = 1\)) and RPA (infinite screening - \(\alpha = 0\)) can be applied. [Edit on GitHub]

Keywords

• SECTION_PARAMETERS

• ALPHA

Keyword descriptions

SECTION_PARAMETERS

Type: enum
Default: W_0
Lone keyword: W_0
Usage: &xc_functional BLYP

Description: Shortcut for the most common functional combinations.

Valid values:

• W_0 The Coulomb interaction is screened by applying DFT energies \(\varepsilon_p^{DFT}\), which is typically used for GW-BSE and often labeled as \(W_0\).

• TDHF The Coulomb interaction is not screened, i.e. \(W_{pq,rs}(\omega=0) \rightarrow v_{pq,rs}\) enters.

• RPA Infinite screening is applied, i.e. \(W_{pq,rs}(\omega=0) \rightarrow 0\).

• ALPHA Arbitrary screening parameter. Specify within section.

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ALPHA

Type: real
Default: -1.00000000E+000
Usage: ALPHA 0.25

Description: Screening parameter similar to the mixing in hybrid functionals used in TDDFT. \(\alpha\) mimicks the screening \(\epsilon^{-1}(\omega)\) and enforces \(W = \alpha v\) in the BSE calculation.

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