DOI: https://doi.org/10.55373/mjchem.v28i1.461

Keywords: Thermodynamic properties, TiO₂ monolayer, DFT, phonon, band gap

Abstract

Based on first-principles calculations, we have computed the optical and thermodynamic response of the monolayer using the CASTEP. During the structural optimization, it was confirmed that total energy was minimized (-39047.76 eV), and the values matched the reputable theoretical number quoted in the literature. We have investigated the structural stability of TiO₂, and the calculation confirms its stability due to the presence of positive frequencies in the spectrum. The thermodynamic behavior was examined generally as a function of temperature. However, few studies have systematically correlated the thermodynamic and optical responses of TiO₂ monolayers under identical DFT parameters. Our estimate of the Debye temperature was approximately 1300 K, indicating that lattice vibrations at room temperature are stiff, suggesting TiO₂ has reasonably good thermal conductivity behavior. The obtained band gap (2.93 eV) and Debye temperature were validated against previous DFT results, differing by less than 10 %. Interestingly, the TiO₂ reached the Dulong-Petit asymptote value at 600 K, which could compete with the well-known thermoelectric material, PbTe. Furthermore, the monolayer TiO₂ exhibits, confirming the model reliability. We have analyzed the dielectric properties and found that the TiO2 absorbs light in the visible region, which is confirmed by the sharp peaks in optical spectra. Thus, the TiO₂ could serve as a potential candidate for optoelectronics and thermal applications.