ELPH_SELFEN_MU

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ELPH_SELFEN_MU = [real array]
Default: ELPH_SELFEN_MU = 0.0

Description: list of chemical potentials at which to compute the electron-phonon self-energy and transport coefficients.

Each chemical potential specified in the list will be added to the Fermi energy determined for the k point grid KPOINTS_ELPH. This Fermi energy might be different from the one determined in the self-consistent calculation if the k point meshes or ELPH_ISMEAR is different from ISMEAR. The Fermi energy from the self-consistent and non-self-consistent calculations can be read from the OUTCAR file. For example

$ grep "Fermi energy" OUTCAR
 Fermi energy:         3.5134142202
 Fermi energy:         3.5314189274 eV (dense k-point grid)

In this example, ELPH_SELFEN_MU means that the chemical potential will be set to

3.5314189274+0.1 eV

.

This can be verified Chemical potential calculation section of the OUTCAR file.

                  Number of electrons per cell
                  ----------------------------
T=      0.00000000    18.00000452
T=    100.00000000    18.00000536
T=    200.00000000    18.00000792
T=    300.00000000    18.00001223
T=    400.00000000    18.00001792
T=    500.00000000    18.00002315

                  ----------------------------
                      Chemical potential
                  ----------------------------
T=      0.00000000     3.63141893
T=    100.00000000     3.63141893
T=    200.00000000     3.63141893
T=    300.00000000     3.63141893
T=    400.00000000     3.63141893
T=    500.00000000     3.63141893
                  ----------------------------

For each of these chemical potentials and temperatures, the number of electrons per cell is computed and reported. These, in turn, can be converted to a carrier density by dividing be the volume of the unit cell. If more than one value is present in ELPH_SELFEN_MU, more columns are added to the list of chemical potentials above and more instances of the electron self-energy due to electron-phonon coupling accumulators are created. The number of rows is governed by the list of temperatures in ELPH_SELFEN_TEMPS.

Alternatively, one can specify the carrier density in units of ${m^{-3}}$ by using the ELPH_SELFEN_CARRIER_DEN tag.