Phase transitions, band structures, elastic and lattice dynamic properties of CdSnV2 (V=P, As, Sb) under pressure from first principles

Ab initio self-consistent calculations have been performed to study the pressure-induced effects on the structural, electronic, elastic and lattice dynamic properties of CdSnV2 (V=P, As, Sb) semiconductors using norm-conserving pseudo-potentials and generalized-gradient approximation in the frame of density functional theory. The optimized structural parameters are well consistent with available experimental and theoretical data. Enthalpy calculations show that CdSnV2 semiconductors undergo a pressure-induced first-order structural phase transition from the chalcopyrite (CH) to the rocksalt (RS) phase. The evolutions of fundamental band-gap energies, single-crystalline elastic constants, polycrystalline elastic moduli, phonon dispersion spectra, IR absorption and Raman scattering spectra, as well as zone-center phonon frequencies with pressure have been investigated in detail. Our results show that the underlying physical origin of CH→RSCH→RS phase transition might be in close relation with the unstable low-frequency phonon modes and the softening shear elastic modulus.