Theoretical studies of elastic properties of orthorhombic LiBH4

We have presented a study of the elastic properties of orthorhombic Pnma structural LiBH4 by first-principles calculations using a projected augmented plane-wave method. The single crystal elastic constants are successfully obtained from the stress-strain relationship calculations and the strain energy-strain curves calculations, respectively. The Shear and Young's moduli as well as Poisson's ratio for ideal polycrystalline LiBH4 are calculated. The bulk moduli are in good agreement with recent experimental and theoretical results. The linear compressibility and the directional dependent Young's modulus are also calculated. The shear anisotropic factors and the elastic anisotropy of Pnma LiBH4 are analyzed. The Debye temperature and the average elastic wave velocity are derived from theoretical elastic constants. According to the obtained results, the Pnma LiBH4 is found to be mechanically stable and ductile at zero temperature and zero pressure.