Pressure-temperature dependence of thermodynamic properties of rutile (TiO2): A first-principles study

Ab-initio calculations of thermal properties of rutile (TiO2) have been performed by using the projector augmented-wave (PAW) method within the generalized gradient approximation (GGA). Both pressure- and temperature-dependent thermodynamic properties such as the bulk modulus, thermal expansion, thermal expansion coefficient, heat capacity at constant volume and constant pressure were calculated using two different models based on the quasiharmonic approximation (QHA): the Debye-Slater and Debye-Gruneisen model with Dugdale-MacDonald (DM) approximation. Also, the empirical energy corrections were applied to the results to correct the systematic errors in the density functional theory. It is found that the Debye-Gruneisen model provides more accurate estimates than the Debye-Slater models, especially after empirical energy correction.