Predicted Structural, Elastic, Electronic, Lattice Dynamic, Thermodynamic and Optical Properties of Cubic SсF₃ from First-Principles Calculations

Abstract

We calculated equilibrium lattice constant ${{a}_{0}}$, bulk modulus $B_{0}^{{}}$, pressure derivative $B_{0}^{'}$ and bond lengths ${{d}_{{{{F}_{i}} - {{F}_{j}}}}}$ and ${{d}_{{{{F}_{i}} - S{{c}_{j}}}}}$ using both GGA and LDA approaches for ScF₃. We predict the elastic moduli using GGA and LDA functional. The ScF₃ is elastically and dynamically stable in the pressure range 0–38 GPa. The Young’s modulus, shear modulus, linear compressibility and Poisson’s ratio have a maximum value and another minimum in each direction explaining their anisotropy. The indirect R–X band gap value of 6.139 eV and the electronic DOS indicate the insulator character in ScF₃. The predicted GGA and LDA values of electron effective masses for ScF₃ are 1.604 and 1.703, respectively. The longitudinal and transversal optical phonon frequencies ω_L0 and ω_T0 at R point for ScF₃ are 725.69 and 588.5 cm^–1. The volumetric thermal expansion coefficient, the constant volume and pressure heat capacities and entropy at zero pressure and 300 K are 5.14 × 10⁵ K^–1, 83.86, 86.54, and 77.48 J mol^–1 K^–1 for ScF₃. The edge of the optical absorption located at 31.53 nm is caused by V₁−C₁ transition at X point, which corresponds to the indirect band gap R–X.