The class of semimetals has emerged as upcoming future devices due to their technological efficient applications. The distinctive component in semimetals is the simultaneous manipulation of spin states along with electronic states that has prompted the discovery of spin ordering at Fermi level. The current investigation is first-principle approach to compute structural, electronic, thermoelectric and vibrational properties of VCo$_2$Al. The systematic anddetailed theoretical investigation based on density functional theory in combination with Boltzmann transport theory has been done for the first time. The structural properties namely lattice constant, bulk modulus and pressure derivative of bulk modulus have been calculated, revealing that VCo$_2$Al gets stiffer on applying pressure. The plotted electronic band structure shows band dispersion at two discrete points at Fermi level specifying VCo$_2$Al to be Weyl semimetal. The joint analysis of electronic band structure and plotted density of states affirms the band dispersion and presence of Weyl electrons at Fermi level. The present investigation purposes VCo$_2$Al as an excellent n-type high temperature thermoelectric material having power factor of $184.3\times 10^{14}$ $\mu$W cm$^{-1}$ K$^{-2}$ s$^{-1}$ at 800 K. The vibrational properties calculated within the framework of density functional perturbation theory uncover the dynamic stability of VCo$_2$Al. The computedphysical properties from these calculations would create new frontiers of experimental work for further realization of innovative applications.

Researchers have looked into quaternary Heusler (QH) compounds for their potential use in futuristic gadgets like photovoltaic cells, optical fibres, thermoelectric modules and spintronic sensors. As per such motivations and research interests, here we are presenting two recently reported Li-based QH compounds LiNbCoAl and LiNbCoGa which are stabilized into face-centred cubic structure of space group F-43m with semiconducting nature. These compounds exhibit high melting temperatures, showing the p-type semiconducting nature and are found to have advantageous thermoelectric capabilities in the high-temperature range. Additionally, the dynamical stability and appropriate elastic and mechanical characteristics for the foundation of effective thermoelectric modules in the temperature range of 1600 K enhance their scientific and technical scope. The electronic band structure is discussed along with the density of states for the betterunderstanding of the electrical properties. The thermodynamic response up to a temperature of 1600 K is also examined for understanding in terms of free energy, specific heat at constant volume and entropy. The special dependences in thetwo and three dimensions are applied and investigated to characterize the anisotropic nature. However all the required thermoelectric properties are calculated and presented, and the highest figure of merit value at 1600 K for both materials is 0.47 for LiNbCoAl and 0.56 for LiNbCoGa, respectively. As per their excellent practical properties, the current study asserts that both QH compounds should really be considered for energy conversion techniques in high-temperature environments. For the complete study prospectus, these materials are being disclosed for the first time here.