Computational discovery of two-dimensional copper chalcogenides Cu X ( X = S, Se, Te)
Résumé
We investigate the energy landscape of 2D CuS, CuSe, and CuTe compounds using a global evolutionary algorithm in combination with density functional theory (DFT). Four low-lying energy Cu2X2 (X=S, Se, Te) slabs with P 3m1, P 4/mmm, P 4/nmm, and P mmn symmetries have been identified on their respective potential energy surfaces. Three structures present tetrahedral CuX4 motifs which pave the 2D slabs, while the latter is based on shared Cu4X2 octahedra. The viability of each phase was examined by looking at dynamical, thermodynamic, and thermal stability criteria. We find that 2D copper monosulfide crystallizes in the P 3m1 phase, reminiscent of the covalent slab found in the CaAl2Si2 prototype. Two polymorphs of 2D copper selenide with symmetries P 3m1 and P 4/mmm are close in energy. The latter Cu2Se2 slab is made of fused Cu4Se2 square bipyramids with electronegative Se atoms in apical positions. Finally, the ground-state 2D-CuTe has a P mmn space group containing distorted CuTe4 tetrahedra with some Te-Te bonding. The electronic and bond analyses show that all of these predicted 2D CuX phases are metallic with iono-covalent bonds.
Domaines
Chimie
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