title: Dispersion of linear and nonlinear optical susceptibilities in calcium neodymium oxyborate Ca4NdO(BO3)3-LDA versus GGA.
abstract: We have performed ab inito theoretical calculations of the electronic structure and the linear and nonlinear optical susceptibilities for calcium neodymium oxyborate Ca4NdO(BO3)3 using two approximations for the exchange correlation (XC) potentials, the local density approximation (LDA) and the generalized gradient approximation (GGA). Our calculations show that this compound is metallic-like, with density of states at the Fermi energy E(F), N(E(F)), of 5.95 and 10.33 states/Ry-cell or bare electronic specific heat coefficients of 1.03 and 1.79 mJ/mol-K2 for LDA and GGA, respectively. The overlap between the valence and conduction bands is strong, resulting in metallic behavior. We found that Nd-s/p/d, Ca-s/p, B-p, and O-s/p states controlled the overlapping around E(F). The effect of LDA and GGA on the band structure, density of states, and linear optical properties is very small, while for the nonlinear optical properties, it is very pronounced. Our calculations show that χ(111)(2)(ω) is the dominant component for both LDA and GGA. We find opposite signs of the contributions of the 2ω and 1ω inter/intraband to the real and imaginary parts for the dominant component throughout the wide optical frequency range.
authors.affiliation: Institute of Physical Biology, South Bohemia University, Nove Hrady 37333, Czech Republic. maalidph@yahoo.co.uk
authors.forename: Ali H
authors.initials: AH
authors.lastname: Reshak
authors.forename: S
authors.initials: S
authors.lastname: Auluck
authors.forename: I V
authors.initials: IV
authors.lastname: Kityk
mesh_terms: D001881:Borates / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004583:Electrons; D015394:Molecular Structure; D009354:Neodymium / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D001881:Borates; D009354:Neodymium; D002118:Calcium