Abstract: Based on the density functional theory, electronic and optical properties of rutile-MgH2 have been investigated using the plane-wave pseudopotential and BFGS approaches.At ground state, rutile-MgH2 crystal has good elasticity stability.The calculated equilibrium structural parameters are in excellent agreement with the experimental and other theoretical results.Mulliken population analysis of rutile-MgH2 indicates that the charge transfers are from Mg to H.The total charge is mainly derived from the Mg2p and H 1s states, and rutile-MgH2 is mixture bonding material (covalent+ionic bond).Combing with the electronic properties and frequency-dependent dielectric function ε(ω), the dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity and loss function of rutile-MgH2 were calculated and investigated in detail.Results indicate that the main absorption ranges of rutile-MgH2 are located in ultraviolet region, rutile-MgH2 has a very strong permeability between 24.88 and 42.35 eV, and in high frequency case, it has a very high reflectivity.

Key words: Based on the density functional theory, electronic and optical properties of rutile-MgH2 have been investigated using the plane-wave pseudopotential and BFGS approaches.At ground state, rutile-MgH2 crystal has good elasticity stability.The calculated equilibrium structural parameters are in excellent agreement with the experimental and other theoretical results.Mulliken population analysis of rutile-MgH2 indicates that the charge transfers are from Mg to H.The total charge is mainly derived from the Mg2p and H 1s states, and rutile-MgH2 is mixture bonding material (covalent+ionic bond).Combing with the electronic properties and frequency-dependent dielectric function ε(ω), the dielectric function, absorption coefficient, refractive index, extinction coefficient, reflectivity and loss function of rutile-MgH2 were calculated and investigated in detail.Results indicate that the main absorption ranges of rutile-MgH2 are located in ultraviolet region, rutile-MgH2 has a very strong permeability between 24.88 and 42.35 eV, and in high frequency case, it has a very high reflectivity.