Cu-Doped KCl Unfolded Band Structure and Optical Properties Studied by DFT Calculations

Abstract

The unfolded band structure and optical properties of Cu-doped KCl crystals were computed by first principles within the framework of density functional theory, implemented in the ABINIT electronic structure package utilizing pseudopotential approximation and a plane-wave basis set. From a theoretical point of view, Cu substitution into pristine KCl crystals requires calculation by the supercell (SC) method. This procedure shrinks the Brillouin zone, resulting in a folded band structure that is difficult to interpret. To solve this problem and gain insight into the effect of copper ions (Cu+) on electronic properties, the band structure of SC KCl:Cu was unfolded to make a direct comparison with the band structure of the primitive cell (PC) of pristine KCl. To understand the effect of Cu substitution on optical absorption, we calculated the imaginary part of the dielectric function of KCl:Cu through a sum-over-states formalism and broke it down into different band contributions by partially making an iterated cumulative sum (ICS) of selected valence and conduction bands. Consequently, we identified those interband transitions that give rise to the absorption peaks due to the Cu+ ion. These transitions involve valence and conduction bands formed by the Cu-3d and Cu-4s electronic states

Structures and stability of the Cu$_{38}$ cluster at finite temperature

“…The optical properties are a source of atomic structural information, and their electronic structure determines them. 116 In this paper the TD-DFT was used to compute the optical absorption spectra in the UV-visible range 0.5 < ω < 2.5 eV for the Cu 38 cluster. We employ the CAM-B3LYP functional, Def2-TZVP basis set, and 50 singlets and 50 triplets states.…”