Band structure of semiconductors and insulators from Koopmans-compliant functionals*

Koopmans-compliant functionals provide a novel orbital-density-dependent framework for an accurate evaluation of spectral properties, obtained imposing a generalized piecewise-linearity condition on the total energy of the system with respect to the occupation of each orbital. In
crystalline materials, due to the orbital-density-dependent nature of the functionals, minimization of the total energy leads to a ground-state set of variational orbitals that are localized and break the periodicity of the underlying lattice. Despite that, thanks to the Wannier-like character of the variational orbitals, we show that the Bloch states can be recovered and it is possible to describe the electronic energies through a band structure picture. In this talk I will present results for some benchmark semiconductors and insulators, obtained by unfolding the electronic bands obtained with direct minimization Gamma-point-only calculations.

[1] I. Dabo, A. Ferretti, N. Poilvert, Y. Li, N. Marzari, M. Cococcioni, Phys. Rev. B 82, 115121 (2010)
[2] N. L. Nguyen, N. Colonna, A. Ferretti, N. Marzari, Phys. Rev. X 8, 021051 (2018)
[3] N. Colonna, N. L. Nguyen, A. Ferretti, N. Marzari, J. of Chem. Theory Comput. 15, 1905 (2019)