title: A first-principles study of linear and nonlinear optical properties of 4-nitro-4'-methylbenzylidene aniline.
abstract: First-principles calculations of two second-order optical response functions as well as the dielectric function for 4-nitro-4(')-methylbenzylidene aniline are performed. Specifically, we evaluate the dielectric function and the second-harmonic generation (SHG) response coefficient over a wide frequency range. Electronic structure obtained from the full-potential projected augmented wave method is adopted in the calculation of optical properties. The calculated results of the refractive indices and the SHG are in good agreement with the experimental values. The linear and nonlinear optical spectra are analyzed and the origins of the peaks in the spectra are discussed in terms of the calculated electronic structure. It is found that the origin of the large nonlinear optical susceptibility is the charge transfer due to the strong "push-pull" effect. The study of the contributions of different transitions to the SHG coefficients shows that the virtual electron process is main. The contribution to the largest component chi(11) ((2)) of the virtual hole process is about 30% of the total static limit of the SHG coefficient. The prominent features in the spectrum of chi(11) ((2)) are successfully correlated with the features of the linear dielectric function epsilon(omega) in terms of single-photon and two-photon resonances.
authors.affiliation: Department of Basic Sciences, Hubei Automotive Industries Institute, Hubei 442002, China. shijunluo21c@yahoo.com.cn
authors.forename: S J
authors.initials: SJ
authors.lastname: Luo
authors.forename: W F
authors.initials: WF
authors.lastname: Du
authors.forename: H Z
authors.initials: HZ
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D000814:Aniline Compounds / Q000737:chemistry*; D003198:Computer Simulation; D004563:Electrochemistry; D004583:Electrons; D004735:Energy Transfer; D016014:Linear Models; D008956:Models, Chemical; D055620:Optical Phenomena
chemical_list: C534431:4-nitro-4'-methylbenzylidene aniline; D000814:Aniline Compounds