Ab initio characterization of the electronic and optical properties of a new IR nonlinear optical crystal: K₃V₅O₁₄

We present detailed investigations of the electronic and optical properties of K₃V₅O₁₄, including the band structure, density of states (DOS), population analysis, dielectric function, refractive index and second-order nonlinear susceptibilities. The calculations are performed using the abinitio pseudopotential density functional method combined with an anharmonic oscillator model, in which we employ the Perdew-Burke- Eruzerhof form of the generalized gradient approximation together with plane-wave basis sets for expanding the periodic electron density. From the band calculation, K₃V₅O₁₄ is predicted to be an indirect band gap semiconductor. From the DOS and population analysis, we find that the bonding between K⁺ and V₅O₁₄ layers is mainly ionic while that between V and O is covalent. It is indicated that the hybridization of V-3d with the O-2p states is very important for the optical properties of K₃V₅O₁₄. The calculated birefringence is large enough to achieve phase-matchable conditions, and our calculated second-harmonic-generation (SHG) coefficients agree with experimental results.