Estudo da propriedade macroscópica de terceira ordem usando a abordagem de supermolécula

Abstract

Organic materials have stood out as a promising area in several applications, including in the field of linear and nonlinear optics. Among the organics that present advantageous characteristics for these applications are chalcones, whose simplicity of structure allows the obtaining of electrical properties, such as polarizability. Molecular polarizability is the response of a molecule to a uniform external electric field. In this work, a supermolecule approach and an iterative electrostatic polarization scheme were used to better understand the electrical properties of the 3MPNP and 4MPMS molecules. It was proposed to adopt three load groups, totaling seven models representing these three groups. The seven charge models (NBO, Mulliken Hirshfield, CM5, MK, Chelp, ChelpG), together with the basis functions 6-311G(d) and 6-311G++(d), were used to determine the essential physical properties, namely: dipole moment, linear polarizability, second hyperpolarizability and third order linear susceptibility. When comparing the results obtained in the CAM-B3LYP functional with the theoretical results obtained from the optical properties of the molecules, it is clear that they are similar, both in 3MPNP and 4MPMS. It is noted that, with the exception of Mulliken's partial atomic charge model, in 3MPNP any charge model can be used to calculate the third-order property, with a 6- 311G++(d) being the best representative mathematical basis function. As for the 4MPMS structure, any charge group, regardless of the basis function used, can represent a viable approach to estimate the third-order susceptibility.