Non‐standard anisotropy of the energy spectrum of a layered TlGaSe₂ crystal

Abstract

Phone: þ48 17 872 11 28, Fax: þ48 17 872 12 83The ab initio band structure calculations of the TlGaSe 2 crystal in the framework of DFT, within LDA were performed using the relevant Brillouin zone for the base-centered monoclinic lattice. It was shown that the main features of this structure can be obtained in the framework of the elementary energy bands concept, taking into account the existence of the Davydov splitting that is the consequence of structural properties of TlGaSe 2 .The obtained results confirm that TlGaSe 2 is an indirect bandgap material, however, an additional local minimum of the conduction band in the G point is located both in a near energetic and near k-space distance from the absolute minimum. It was shown that TlGaSe 2 is the next example of a layered semiconductor for which an universal anisotropy of the energy spectrum branches that coincide with its mechanical anisotropy cannot be established.

Electron-Deformational Phase Transitions in a TlGaSe2Layered Crystal

“…The band structure of the TlGaSe 2 layered crystal has been calculated initially by means of the semi-empirical pseudopotential method [11,12], and next by ab initio methods [13], however in an inappropriate Brillouin zone. Our recent ab initio DFT-based calculations within a relevant BZ of the monoclinic base-centered lattice [14] have revealed that the band structure of TlGaSe 2 exhibits a complicated form in the vicinity of the energy gap, see Fig. 1, right.…”