Structure and vibrational spectra of calcium hydride and deuteride

We have investigated the structure, energetics, and dynamics of calcium hydride (CaH2) and calcium deuteride (CaD2). The crystal structure of CaD2 (space group Pnma) was determined in detail using high-resolution neutron powder diffraction (NPD) data at both 9 and 298 K. The structure is in excellent agreement with the optimized structure derived from first-principles calculations. The phonon calculations based on the optimized structure reproduce well the phonon density of states of CaH2 (and CaD2) measured by neutron vibrational spectroscopy (NVS). The combined NPD and NVS results reveal the complete structural and dynamical details for CaH2 (CaD2).