First-principles calculations of electronic, vibrational, and structural properties of scheelite EuWO4under pressure

In this paper we report a density functional study of the structural, electronic, and vibrational properties of the EuWO${}_{4}$ compound in the scheelite structure. We use Raman spectroscopy to complement the study for this phase at ambient pressure. The first part of the paper is devoted to analyzing the results obtained with the Perdew-Burke-Ernzerhof for solids exchange-correlation functional within the $\mathrm{GGA}+U$ approximation and compare those with our experimental results and reported available data. We also present the evolution of these properties, for the same crystal structure, up to 8 GPa. The second part of the paper is devoted to discussing our study on the high-pressure phase transitions of EuWO${}_{4}$, for which we follow the evolution of the structural properties as a function of pressure. The results show that the high-pressure behavior of EuWO${}_{4}$ is very similar to that of CaWO${}_{4}$, SrWO${}_{4}$, BaWO${}_{4}$, and PbWO${}_{4}$, for which the scheelite structure undergoes a phase transition to the fergusonite structure, an observation also supported by our experimental data. Additionally, we can also conclude that at higher pressures, EuWO${}_{4}$ evolves to the BaWO${}_{4}$-II and Cmca crystal phases.