  A DFT study of the synthesized MAX phase Zr2SeC has been carried out for the
first time to explore its physical properties for possible applications in many
sectors. The studied properties are compared with prior known MAX phase Zr2SC.
The structural parameters (lattice constants, volume, and atomic positions) are
observed to be consistent with earlier results. The band structure and density
of states (DOS) are used to explore the metallic conductivity, anisotropic
electrical conductivity, and the dominant role of Zr-d states to the electrical
conductivity. Analysis of the peaks in the DOS and charge density mapping (CDM)
of Zr2SeC and Zr2SC revealed the possible variation of the mechanical
properties and hardness among them. The mechanical stability has been checked
using elastic constants. The values of the elastic constants, elastic moduli
and hardness parameters of Zr2SeC are found to be lowered than those of Zr2SC.
The anisotropic behavior of the mechanical properties has been studied and
analyzed. Technologically important thermodynamic properties such as the
thermal expansion coefficient, Debye temperature, entropy, heat capacity at
constant volume, Gruneisen parameter along with volume and Gibbs free energy
are investigated as a function of both temperature (0 to 1600 K) and pressure
(0 to 50 GPa). Besides, the {\Theta}D, minimum thermal conductivity (Kmin),
melting point (Tm), and {\gamma} have also been calculated at room temperature
and found to be lowered for Zr2SeC compared to Zr2SC owing to their close
relationship with the mechanical parameters. The value of the {\Theta}D, Kmin,
Tm, and TEC suggest Zr2SeC as a thermal barrier coating material. The
dielectric constant (real and imaginary part), refractive index, extinction
coefficient, absorption coefficient, photoconductivity, reflectivity, and loss
function of Zr2SeC are computed and analyzed.
