First-principles study of phonons, optical properties, and Raman spectra in MgV2O5

The electronic properties of MgV(2)O(5) are calculated in the framework of the all-electron full-potential linearized augmented plane-wave method within density-functional theory. Adopting the experimental lattice parameters, all atomic positions inside the unit cell are optimized. It is shown that this relaxation has a strong effect on the bond lengths and hence the electronic bands, The optical properties are determined within the independent-particle approximation. In addition, the fully symmetric A(g) phonon modes are calculated by the frozen phonon approach. For each eigenvector, the dielectric tensor is obtained as a function of the displacement coordinates. Based on these results, the corresponding Raman spectra are determined and discussed in the context of experimental data. Theory is able to either confirm or revise the assignment of the measured spectra. Finally, the calculated properties are compared with those of other vanadium ladder structures.