Prediction of half-metallic properties for the AMnSe2 (A=Rb, Cs) compounds from first-principle calculations

•Some physical properties of the AMnSe2 layered compounds have been predicted.•The considered crystals are very soft materials and mechanically stable.•The examined materials are found to be half-metallic.•The magnetic moment is mainly originated from the transition metal Mn.

Using first-principle calculations method based on spin-polarized density functional theory, we have predicted the half-metallic character of the AMnSe2 (A=Rb, Cs) layered compounds. The structural, electronic, magnetic and elastic properties of these ternary chalcogenides crystals have been investigated. The electronic exchange-correlation energy has been described by the generalized gradient approximation GGA and the GGA+U (U   is the Hubbard correction). Our calculated structural parameters are in good agreement with the available experimental data. The calculated total magnetic moment is equal to 4.00 μBμB for both studied compounds. Architecture of the electronic states near the Fermi level has been explored and the origin of the gap in the considered half-metallic alloys has been determined. Single-crystals and polycrystals elastic moduli and related properties for both investigated materials have been examined.