A density functional study of second-order susceptibilities in calcium samarium oxyborate Ca4SmO(BO3)3

Abstract

We report calculations of the linear and nonlinear optical susceptibilities (second harmonic generation) for calcium samarium oxyborate Ca4SmO(BO3)3 using the full-potential linear augmented plane wave method. Our calculations show that this compound is metallic-like with density of states at the Fermi energy EF, N(EF) = 421.6 states/Ry-cell or a bare electronic specific heat coefficient of 73.14 mJ mole−1 K−2. We find that the metallic behaviour is due to the strong overlap of the Sm and O states around EF. We have performed calculations for the two contributions to ε(ω), namely, intra-band and inter-band transitions. The effect of the intra-band term is significant for energies less than 1 eV. We have calculated the various components of the second-order susceptibility tensor and find that is the dominant component. We find opposite signs for the contributions of 2ω and 1ω inter-/intra-band to the real and imaginary parts of the dominant component throughout the wide optical frequency range.