Investigation of the linear and second-order nonlinear optical properties of molecular crystals within the local field theory

Abstract

In this paper it is shown that modest calculations combining first principles evaluations of the molecular properties with electrostatic interaction schemes to account for the crystal environment effects are reliable for predicting and interpreting the experimentally measured electric linear and second-order nonlinear optical susceptibilities of molecular crystals within the experimental error bars. This is illustrated by considering two molecular crystals, namely: 2-methyl-4-nitroaniline and 4-(N,N-dimethylamino)-3-acetamidonitrobenzene. Three types of surrounding effects should be accounted for (i) the polarization due to the surrounding molecules, described here by static electric fields originating from their electric dipoles or charge distributions, (ii) the intermolecular interactions, which affect the geometry and particularly the molecular conformation, and (iii) the screening of the external electric field by the constitutive molecules. This study further highlights the role of electron correlation on the linear and nonlinear responses of molecular crystals and the challenge of describing frequency dispersion.

Which charge definition for describing the crystal polarizing field and the χ(1) and χ(2) of organic crystals?

“…[22][23][24] Subsequently, these dressed properties were employed within electrostatic interaction schemes to evaluate the macroscopic susceptibilities, w (1) and w (2) . [22][23][24] Subsequently, these dressed properties were employed within electrostatic interaction schemes to evaluate the macroscopic susceptibilities, w (1) and w (2) .…”

“…[22][23][24] Subsequently, these dressed properties were employed within electrostatic interaction schemes to evaluate the macroscopic susceptibilities, w (1) and w (2) . In these studies, the following observations have been made: (i) the oscillatory dependence (or slow convergence), as a function of the radius of the sphere containing point charges, of the electric field inside the QM cluster only affects the molecular properties to a small extent and the macroscopic ones even less, (ii) imposing the neutrality of the spherical cluster leads to incorrect description of the in-crystal polarizing field, 22 and (iii) the excess charge shifts the polarizing potential but does not affect the polarizing electric field since the gradient of a constant is zero. EIM, EEIM, or SCREEP and might not be sufficient for predicting NMR parameters, it provides an efficient tool to predict w (1) and w (2) of organic molecular or ionic crystals.…”

Effects of Changing Substituents on the Non-Linear Optical Properties of Two Coumarin Derivatives

“…In the SM method, the atoms that form the surrounding molecules of the compounds are treated as point charges, since the interactions between molecules have a dominant electrostatic nature, taking into account long-range electrostatic effects [28,29]. Another alternative model to estimate χ (1) and χ (2) was proposed by Seidler and Champagne [30][31][32][33][34][35] with very good results.…”

A DFT Study of Linear and Nonlinear Optical Properties of 2-Methyl-4-nitroaniline and 2-Amino-4-nitroaniline Crystals

“…The linear and nonlinear optical properties of MNA have already been the topic of several experimental 2-6 and theoretical [7][8][9][10][11][12] studies. The FT-IR spectra of crystalline MNA deposited on a poly substrate were studied by Vallee and coworkers [13][14] .…”