Investigation of structural, elastic, and lattice-dynamical properties of Ca2Si, Ca2Ge, and Ca2Sn based on first-principles density functional theory

• The DFT calculations have been performed for Ca2Si, Ca2Ge, and Ca2Sn compounds.
• The elastic properties of these compounds were predicted theoretically.
• Linear response theory was used to calculate the lattice-dynamical properties.
• The thermodynamic properties such as Svib and Cv were predicted theoretically.

The structural, elastic, phonon and thermodynamic properties of orthorhombic Ca2X (X = Si, Ge, and Sn) were systematically investigated using first-principles density functional theory (DFT). The elastic constants (cij), elastic modulus (B, G, E), Poisson’s ratio (ν), and elastic Debye temperature (ΘD) were determined and compared with the results of previous calculations. For the first time, linear response theory is used to calculate the phonon dispersion relation and phonon density of states for these compounds as well as their infrared and Raman active mode frequencies. In this study, the thermodynamic properties such as vibrational entropy (Svib) and constant-volume specific heat (Cv) were predicted theoretically and discussed.

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