Polarization effects on the third-order nonlinear optical properties of two polymorphs of enamine derivative

Abstract

In this report, we start from ab initio calculations to get the structural properties isolated molecule of an organic crystal. Since the knowledge of the effects caused by its neighboring molecules is necessary for an appropriated description of the nonlinear optical properties in the solid state, a more efficient design of such materials also requires theoretical models describing in detail the structural and electrical properties of the crystalline environment. The structural descriptions of monoclinic (M) and orthorhombic (O) polymorphs of the (1E)-N′-[(E)-2-cyano-1-(dimethylamino)-2-nitrovinyl]-N,N-dimethyl-ethanimidamide (DMEI, M, and O) were previously reported in the literature and here we use the supermolecule plus the Hirshfeld surface supramolecular approaches to get some interesting features, increasing our understanding about this enamine derivative. The dipole moment, the linear polarizability, and second hyperpolarizability of the asymmetric unit of the (M and O) DMEI are investigated through a supermolecule approach in combination with an iterative scheme where electrostatic interactions of the atoms of the embedded molecules are represented by point charges. In addition to calculations, other interesting results are obtained when we compare the results for isolated molecule and the molecule under the influence of its crystalline environment for the static and dynamic cases; under such influence we have found very interesting results, e.g., the large value of the average second hyperpolarizability, about 19,900 % greater than the value for the isolated molecule in the static case.