  Beta-PtO2 is a useful transition metal dioxide, but its fundamental
thermodynamic and elastic properties remain unexplored. Using first-principles
calculations, we systematically studied the structure, phonon, thermodynamic
and elastic properties of beta-PtO2. The lattice dynamics and structural
stability of beta-PtO2 under pressure were studied using the phonon spectra and
vibrational density of states. The vibrational frequencies of the optical modes
of beta-PtO2 increase with elevating pressure; this result is comparable with
the available experimental data. Then, the heat capacities and their pressure
responses were determined based on the phonon calculations. The pressure
dependence of the Debye temperature was studied, and the results are compared
in two distinct aspects. The elastic moduli of beta-PtO2 were estimated through
the Voigt-Reuss-Hill approximation. The bulk modulus of beta-PtO2 increases
linearly with pressure, but the shear modulus is nearly independent of
pressure. Our study revealed that the elastic stiffness coefficients C44, C55
and C66 play a primary role in the slow variation of the shear modulus.
