band_gap_reference

Calling sequence

classical{ band_gap_reference = ... }

Properties

  • usage: \(\mathrm{\textcolor{ForestGreen}{optional}}\)

  • type: real number

  • values: \(0.0 \leq r \leq 1.0\)

  • default: not defined

  • unit: \(\mathrm{-}\)

Functionality

The conduction band minimum is always defined as \(E_c = VBO + E_g\), where \(E_g\) is the energy gap and \(VBO\) is defined depending on this keyword. By default, when the keyword is not set to any value, \(VBO\) is defined as the edge energy of teh top valence band. Otherwise, a superposition is used.

\[VBO = E_{v,av} + (1-r) \cdot E_1 + r \cdot E_2,\]

where, \(E_{v,av}\) is the average energy of the valence bands (as without spin-orbit and crystal-field interactions), \(r\) is the parameter, \(E_1\) is always classified in the output as HH, and \(E_2\) is classified as LH or SO in the output.

As a result of using this keyword, a kink in the conduction band profile is removed for graded alloys in which one observes crossing between two top valence bands.

Warning

Using this keyword effectively alters values of the actual band gap resulted from the obtained profiles. Readjusting material parameters of the band gap are expected to be needed if one needs very accurate calculations of optical transitions.

Note

This feature is a temporary solution for removing artifacts from charge densities in the conduction bands. We are planning on replacing it in the future with a better solution.

Last update: 2025-09-09