First-principles study of structural, electronic, elastic and dielectric properties of RbLi2(NH2)3, LiH and LiNH2

Based on the first-principles density-functional theory, the structural, electronic, elastic and dielectric properties of RbLi2(NH2)3, LiH and LiNH2 are calculated. We have analyzed the bond information in detail, where the atom Li in crystal is represented in ionic characteristics mostly. The small covalent bond behaviors are also captured between atom Li and others. The ionic characteristics with tiny covalent bonds are obviously beneficial to electrons for storage capacity and transferring. The mechanical properties of three crystals reveal that LiH has a strong resistance to deformation. It is predicted that LiH has a long service life as a battery in terms of deformation. The dielectric constant reveals that LiH has a better storage capacity than that of LiNH2. Additionally, LiH has low formation energy, where the harder substance is, the easier formation is.