Structural, stability, electronic, optical and thermodynamic properties of hydrogenated germanene using first-principle calculations

First-principle calculations are performed to study the structural, electronic, optical and thermodynamic properties of hydrogenated germanene (germanane) for most stable chair (C-), boat (B-) and tricycle (T-) structures. The band structure is studied under different hydrostatic pressures. The germanane shows metallic behavior at 30 GPa, 25 GPa and 12 GPa external pressures, respectively, for C-, B- and T-configurations. The calculated binding energy shows that germanane becomes unstable at 30 GPa, 25 GPa and 6 GPa for C-, B- and T-conformers, respectively. The thermodynamic properties of germanane are calculated in the temperature range of 5-1000 K and compared with germanene. The optical parameters such as dielectric constant, refractive index, birefringence, and plasmon energies (h omega(p)) have been calculated for the first time. The calculated values are in good agreement with the experimental and reported values.