Correlação entre densidade eletrônica e propriedades eletro-ópticas em cristais: distribuição de polarizabilidade em biomoléculas e seus agregados moleculares

Abstract

This work focuses on predicting electro-optical properties in biomolecules and amino acid complexes, with an emphasis on polarizabilities, dipole moments, and their macroscopic implications. Using methods based on Quantum Theory of Atoms in Molecules (QTAIM), atomic and functional group polarizability tensors were computed for polypeptides, peptide clusters, and amino acid complexes with transition metals. Isotropic and anisotropic polarizabilities were analyzed to understand how functional groups, such as peptide bonds and sulfur-containing groups (-SH, -S-S-, and -SCH3), influence linear optical responses and macroscopic properties, including refractive indices and birefringence. These sulfur groups exhibited transferability, maintaining stable electronic properties across different molecular environments, making them predictable additive units. Electronic structure calculations were performed using DFT methods with functionals such as CAM-B3LYP and M08-HF, combined with basis sets like aug-cc-pVDZ. Mutual polarization and local field effects were modeled using approaches such as the Atom-Dipole Interaction Model (ADIM). The proposed methodology proved effective in estimating the optical properties of large molecules and aggregates, with potential applications in the rational design of organic materials for optical technologies. Our study provides robust tools for predicting and understanding the electro-optical properties of complex molecular systems, highlighting the role of covalent and non-covalent interactions, such as hydrogen bonding, in determining macroscopic properties.