The prediction of structural, electronic, optical and vibrational behavior of ThS2 for nuclear fuel applications: a DFT study

Using first-principles calculations, we have investigated the structural, electronic, optical, thermodynamic and vibrational properties of Thorium disulfide (ThS2) in Pnma symmetry. Structural properties are explored using CASTEP simulation code along with Generalized Gradient Approximation. Values of lattice parameters (a=7.27 angstrom, b=4.33 angstrom and c=8.56 angstrom) determined in the present work are found in good agreement with the former studies. After geometry optimization of the crystal structure of ThS2, electronic properties containing the electronic band structure, total density of states and partial density of states have been investigated. ThS2 shows direct energy band gap of 0.995 eV, thus, it belongs to semiconducting materials. Optical analysis discloses that maximum absorption occurs in the UV range of the electromagnetic spectrum. Vibrational properties investigated through density functional perturbation theory depict no imaginary or negative frequencies in the phonon spectrum, leading to its dynamical stability. A low frequency optical mode of vibration showing symmetric stretching has been noticed at 40.53 cm(-1) frequency. In order to seek thermo-dynamical stability of thorium disulfide, thermodynamic properties were calculated using harmonic approximation, making thorium disulfide suitable for thermodynamic applications.

Automated summary

Through first-principles calculations, this study investigated the structural, electronic, optical, thermodynamic, and vibrational properties of ThS2. Results showed that ThS2 is a semiconductor with good dynamical stability, suitable for thermodynamic applications.