In this work, the electronic structure and optical behavior and the thermoelectric performance of the known HfNiSn compound have been studied under the substitution of Mn transition metal instead of Ni atoms. Necessary calculations are performed in the framework of DFT first principles studies by applying generalized gradient approximation (PBE-GGA) as well as solving Boltzmann’s semi-classical equations. The entering Mn leads to a change in the electronic structure of HfNiSn and the occurrence of half-metallic ferromagnetic behavior with 100% polarization at the Fermi level. The maximum ZT value obtained for HfMnSn shows that HfNiSn would be suitable for thermoelectric applications at room temperature, both in pure and Mn presence. The examination of optical parameters also indicates good absorption in the visible range for this compound in all cases.

Mechanical, electronic, thermodynamic phase diagram and optical properties of the FeVSb half-Heusler have been studied based on the density functional theory (DFT) framework. Studies have shown that this structure in the MgAgAs-type phase has static and dynamic mechanical stability with high thermodynamic phase consistency. Electronic calculations showed that this compound is a p-type semiconductor with an indirect energy gap of 0.39 eV. This compound’s optical response occurs in the infrared, visible regions, and at higher energies its dielectric sign is negative. The Plasmon oscillations have occurred in 20 eV, and its refraction index shifts to zero in 18 eV.

The electronic, optical and thermoelectric properties of MoS2 nano-sheet in presence of the Ru impurity have been calculated by density functional theory framework with Generalized Gradient approximation. The MoRuS2 nano-sheet electronic structure was changed to the n-type semiconductor by 1.3 eV energy gap. The optical coefficients were shown that the loosing optical energy occurred in the higher ultraviolet region, so this compound is a promising candidate for optical sensing in the infrared and visible range. The thermoelectric behaviors were implied to the good merit parameter in the 100K range and room temperatures and also has high amount of power factor in 600K which made it for power generators applications.