  We have studied the physical properties of M2InC (M = Zr, Hf and Ta) MAX
phases ternary carbides using density functional theory (DFT) methodology. The
structural, elastic and electronic properties are revisited (and found to be in
good agreement with recently reported results). The charge density
distribution, Fermi surface features, Vickers hardness, dynamical stability,
thermodynamics and optical properties have been investigated for the first
time. The calculated single crystal elastic constants and phonon dispersion
curves endorse the mechanical and dynamical stability of all the compounds
under study. The calculated single crystal elastic constants Cij and
polycrystalline elastic constants are found to increase with increasing atomic
number of M species (M = Zr, Hf and Ta). The values of Pugh ratio and Poisson
ratio revealed the brittleness of the compounds under study associated with
strong directional covalent bond with a mixture of ionic contribution.
Overlapping of conduction band and valence band at Fermi level notify the
metallic nature of M2InC (M = Zr, Hf and Ta) MAX phases. Low values of Vicker
hardness indicate the softness of the materials and easy machinability.. The
thermodynamic properties, such as the free energy, enthalpy, entropy, specific
heat capacity and Debye temperature are evaluated using the phonon dispersion
curves and a good correspondence is found with the M atomic species.
Electronically important optical properties, e.g., dielectric functions,
refractive index, photoconductivity, absorption coefficient, loss function and
reflectivity are calculated and discussed in detail in this study.
