Mechanical and chemical bonding properties of ground state BeH ₂

The crystal structure, mechanical properties and electronic structure of ground state BeH ₂ are calculated employing the first-principles methods based on the density functional theory. Our calculated structural parameters at equilibrium volume are well consistent with experimental results. Elastic constants, which well obey the mechanical stability criteria, are firstly theoretically acquired. The bulk modulus B, Shear modulus G, Young's modulus E, and Poisson's ratio υ are deduced from the elastic constants. The bonding nature in BeH ₂ is fully interpreted by combining characteristics in band structure, density of states, and charge distribution. The ionicity in the Be-H bond is mainly featured by charge transfer from Be 2s to H 1s atomic orbitals while its covalency is dominated by the hybridization of H 1s and Be 2p states. The Bader analysis of BeH ₂ and MgH ₂ are performed to describe the ionic/covalent character quantitatively and we find that about 1.61 (1.6) electrons transfer from each Be (Mg) atom to H atoms.