Title: Computational insight on the structural, mechanical and thermal properties of Cu₂CdSnSe₄ and Cu₂HgSnSe₄ adamantine materials
Author(s):

	S. Bensalem (Centre de Développemen des Energies Renouvelables, CDER, BP 62 Route de l'Observatoire Bouzaréah, 16340 Algiers, Algeria),
	M. Chegaar (Département de Physique, Faculté des Sciences, Université Sétif 1, 19000 Sétif, Algeria; Laboratoire d'Optoélectronique et Composants, Université Sétif 1, 19000 Sétif, Algeria),
	A. Bouhemadou (Laboratory for Developing New Materials and their Characterization, University of Setif 1, Setif 19000, Algeria)

Through first-principles calculation based on the density functional theory (DFT) within the pseudo potential-plane wave (PP-PW) approach, we studied the structural, mechanical and thermal properties of Cu₂CdSnSe₄ and Cu₂HgSnSe₄ adamantine materials. The calculated lattice parameters are in good agreement with experimental and theoretical reported data. The elastic constants are calculated for both compounds using the static finite strain scheme. The hydrostatic pressure action on the elastic constants predicts that both materials are mechanically stable up to 10 GPa. The polycrystalline mechanical parameters, i.e., the anisotropy factor (A), bulk modulus (B), shear modulus (G), Young's modulus (E), Lame's coefficient (λ) and Poisson's ratio (ν) have been estimated from the calculated single crystal elastic constants. The analysis of B/G ratio shows that the two studied compounds behave as ductile. Based on the calculated mechanical parameters, the Debye temperature and the thermal conductivity have been probed. In the framework of the quasi-harmonic approximation, the temperature dependence of the lattice heat capacity of both crystals has been investigated.

Key words: first-principles, structural parameters, mechanical characteristics, thermal properties, Cu₂CdSnSe₄, Cu₂HgSnSe₄
PACS: 63.20.dk, 62.20.D-, 62.20.fk, 65.40.Ba

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