relying on the density matrix D for the description of one-electron and exact exchange contributions, h and E EX , while the plane-wave density n(G) is used to compute electrostatic and XC contributions, E es and E XC . Ω UC is the unit cell volume. Relying on Ewald summation, a core charge compensation potential has been removed from the external potential contribution to h and added to the electronic electrostatic terms. These are divided into Coulomb, self and overlap energy contributions, thus including core compensation charges n c (G) with the total charge distribution being given as