First-principles study on the lattice dynamics and thermodynamics properties of CaFe2As2

The lattice dynamics of room temperature tetragonal phase of CaFe2As2 is studied by first-principles calculations based on the ab initio pseudopotential and plane wave basis. Phonon spectrum throughout the Brillouin zone is obtained using the density-functional perturbation theory within the linear response method. The frequencies of the Raman active modes, phonon density of states and lattice heat capacity are compared with the experimental measurements. The differences between our calculations and experimental measurements in the high-frequency region in phonon density of states are due to the interplay between phonons and spin.