Electronic, thermal and optical properties of Fm-3m HgF2 material: A DFT approach

In this paper, Fm-3m structure of HgF2 has been studied using the density functional theorem (DFT). The stability of this structure is revealed by the positive phonon frequencies of the phonon dispersion curves and by satisfying Born Huang criteria concerned with elasticity of the structure. For the very first time, the elastic constants C11, C12 and C44 of Fm-3m structure of HgF2 have been explored using thermo_pw package. The ductile nature of HgF2 is evidenced by its B/GH ratio of 2.56. The linear response approach has been used to evaluate the intrinsic thermodynamic characteristics of HgF2 while examining the temperature fluctuations of the Helmholtz free energy (F), internal energy (E), specific heat at constant volume (C-v), and Debye temperature (Theta D). The ionic behavior of HgF2 is demonstrated by the broad valence bandgap that is present in the electronic band structure and density of states. Moreover, the hybridization between "s", "p", and "d" orbitals in HgF2 is defined by the charge density along the [110] plane. The static refractive index of HgF2 is 1.26. The broad optical investigation demonstrates Fm-3m HgF2's transparency in the UV and visible spectrums. Additionally, it exhibits considerable UV absorption throughout its range as well as with absorption tail that continues into the visible spectrum. The overall optical parameters of Fm-3m HgF2 show non-linear optical behavior which makes the material to be useful in ultraviolet (UV) photo-sensing devices.