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Abstract In this paper, van der Waals heterostructures consisting of MX 2 (M = Zr, Hf and X = S, Se) monolayers are modeled. The favorable stacking and stability of the modeled monolayer heterostructures are confirmed through binding energy and phonon dispersion calculations. After confirming stability, the electronic and thermoelectric properties of these compounds are explored using the first-principles calculations combined with semiclassical Boltzmann transport theory. It is found that type-II band alignment in ZrS 2 HfSe 2 facilitates charge separation for optoelectronics and solar energy conversion. All studied heterostructures show remarkably higher electrical conductivity than corresponding monolayers, responsible for large power factor values, especially at 1200 K. These findings indicate that the creation of van der Waals heterostructures from MX 2 may be promising for efficient optoelectronic and thermoelectric devices. Highlights • First-principles study of structural, electronic and thermoelectric performance of van der Waals heterostructures of MX 2 (M = Zr, Hf and X = S, Se) monolayers. • Dynamical stability of all under study heterostructures. • Type-II band alignment in ZrS 2 -HfSe 2. • van der Waals heterostructures of MX 2 (M = Zr, Hf and X = S, Se) are promising for efficient optoelectronic and thermoelectric devices. [ABSTRACT FROM AUTHOR]

Osmium based perovskites AOsO 3 (A=Ca, Sr and Ba) have been studied theoretically using density functional theory approach. These studies show that CaOsO 3 and SrOsO 3 are orthorhombic and BaOsO 3 is cubic and are consistent with the experiments. The electronic band structures demonstrate that these compounds are metals. The magnetic studies verify the experimental observations at low temperature, where the spin effects are canceled by the orbitals. The stable magnetic phase optimizations and magnetic susceptibilities calculations by the post-DFT treatment confirm that CaOsO 3 and SrOsO 3 are weak ferromagnetic whereas BaOsO 3 is a paramagnetic material. The directional magnetic study shows that these compounds are magnetically anisotropic, and reveals that the easy magnetization axis is [001] direction. [ABSTRACT FROM AUTHOR]