Key points are not available for this paper at this time.
The band structure from the reduced density-matrix functional theory with an entropic functional for correlation has a simple mathematical structure following the Fermi-Dirac distribution, which accommodates a band gap according to the occupation numbers of the lowest conduction band and the highest valence band. Calculations are demonstrated for Si and diamond with the exchange energy approximated using the Xα model.
Irimia et al. (Wed,) studied this question.