title: Dispersion of linear, nonlinear optical susceptibilities and hyperpolarizability of C11H8N2O (o-methoxydicyanovinylbenzene) crystals.
abstract: Linear and nonlinear optical susceptibility dispersion and hyperpolarizability of C(11)H(8)N(2)O, o-methoxydicyanovinylbenzene, crystals were performed by means of density functional theory (DFT). The exchange and correlation potential was described within a framework of the local density approximation (CA-LDA) and gradient approximation (GGA) based on exchange-correlation energy optimization to calculate the total energy. Engel-Vosko generalized gradient approximation (EV-GGA) and the modified Becke-Johnson potential (mBJ) were used for the electronic crystal structure and optical susceptibility dispersion calculations. We have established systematically increasing energy gap from 2.25 eV (LDA), 2.34 eV (GGA), 2.50 eV (EVGGA), and 2.96 eV (mBJ). The crystal possesses a direct band gap which is an important key factor to make the crystal optically active with high linear and nonlinear optical susceptibilities and hyperpolarizability. Additionally, the studied crystal has a considerable anisotropy of birefringence which is necessary for phase matching conditions during the optical second harmonicexperiments. We have found that the theoretically evaluated second harmonic generation achieves about 5.8 × 10(-8) esu in good agreement with the experimental value (4.9 × 10(-8) esu). Additionally, we have found that our calculated value of β(222) is about 2.3 × 10(-30) esu at zero energy and 6.6 × 10(-30) esu at λ = 1.064 μm. We should emphasize that our calculated value of β(222) (6.60 × 10(-30) esu at λ = 1.064 μm) shows better agreement with the experimental data (5.04 × 10(-30) esu at λ = 1.064 μm) than other calculations.
authors.affiliation: School of Complex systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333, Czech Republic. maalidph@yahoo.co.uk
authors.forename: Ali H
authors.initials: AH
authors.lastname: Reshak
authors.forename: H
authors.initials: H
authors.lastname: Kamarudin
authors.forename: I V
authors.initials: IV
authors.lastname: Kityk
authors.forename: S
authors.initials: S
authors.lastname: Auluck