Ab initio study of electronic, magnetic and optical properties of CuWO4 tungstate

Ab initio LCAO study of the atomic, electronic and magnetic structures and the lattice dynamics of triclinic CuWO4

“…The DFT functionals underestimate the band gap value as expected. Note that our LCAO result (E g =0.54 eV) and the result obtained using the spin-polarised FP-LAPW method [22] coincide when the same generalised-gradient approximation (GGA) is used for the exchangecorrelation potential. The two hybrid functionals PBE0-13% and WCGGA-PBE-16% yield close values of 2.32 eV and 2.56 eV, respectively, which are close to the experimental value of 2.3 eV [19].…”

“…The valence-band XPS spectrum for CuWO 4 shows a broad main peak with weakly resolved shoulder at the lower binding energies states with an admixture of the empty Ni 3d states [29]. Note that in the The electronic band structure by LCAO qualitatively agrees with that obtained in [22] using the spin-polarised FP-LAPW method. Both methods predict a similar origin of the subbands, but their separation, i.e., the gap values, differ slightly.…”

“…Both methods predict a similar origin of the subbands, but their separation, i.e., the gap values, differ slightly. However, this difference can be mostly reduced by performing spin-polarised FP-LAPW calculations with the Hubbard-type Coulomb correction added in the framework of the so-called LDA+U method [22].…”

“…To the best of our knowledge, until now, the band structure of CuWO 4 has been theoretically studied using only the full-potential linearised augmented plane wave (FP-LAPW) method by two groups [20,21] and [22]. Although both groups have used the same FP-LAPW method, different values of the band gap have been found.…”

“…Although both groups have used the same FP-LAPW method, different values of the band gap have been found. The gap value of 1.9 eV has been obtained in [20,21], which is unusually large for the employed exchange-correlation potential within the generalised-gradient approximation (GGA), whereas in [22], the energy gaps of E g ∼0.54 eV and ∼1.5 eV have been found within the local spin density approximation (LSDA) and the local density approximation with the added Hubbard-type Coulomb correction (LDA+U ), respectively. Note that in these works, the calculations have been performed for an experimental CuWO 4 structure without structure optimisation.…”