ELPH SELFEN NW

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ELPH_SELFEN_NW = [integer]
Default: ELPH_SELFEN_NW = 1 

Description: Number of energies to use when computing the phonon-induced electron self-energy.

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The electron self-energy, $\Sigma_{n \mathbf{k}}(\omega)$, depends on the frequency $\omega$ (or energy $\hbar \omega$). ELPH_SELFEN_NW controls the number and location of frequencies when computing the self-energy in the following way:

ELPH_SELFEN_NW > 0

The self-energy is computed at ELPH_SELFEN_NW equally spaced energies between $\varepsilon_{n \mathbf{k}} - \frac{1}{2} E^{\text{W}}$ and $\varepsilon_{n \mathbf{k}} + \frac{1}{2} E^{\text{W}}$. The interval is centered around each Kohn-Sham eigenvalue, $\varepsilon_{n \mathbf{k}}$, and its width, $E^{\text{W}}$, is controlled via ELPH_SELFEN_WRANGE. If ELPH_SELFEN_NW is an even number, it is automatically increased by one so that the center-most energy in each interval always coincides with the corresponding Kohn-Sham eigenvalue.

ELPH_SELFEN_NW < 0

The self-energy is computed at |ELPH_SELFEN_NW| equally spaced energies between $\varepsilon^{\text{min}}_{\mathbf{k}} - \frac{1}{2} E^{\text{W}}$ and $\varepsilon^{\text{max}}_{\mathbf{k}} + \frac{1}{2} E^{\text{W}}$, where $\varepsilon^{\text{min}}_{\mathbf{k}}$ and $\varepsilon^{\text{max}}_{\mathbf{k}}$ are the minimum and maximum Kohn-Sham eigenvalues of the calculation, respectively. Once again, $E^{\text{W}}$ is controlled via ELPH_SELFEN_WRANGE and allows to extend the interval in both directions.