ChemBOS software: Implementações computacionais e investigação do efeito Jahn-Teller em metais de transição

Abstract

The properties of chemical bonds are among the main focuses of theoretical chemistry. A relevant phenomenon in this context is the Jahn-Teller (JT) effect, which causes symmetry breaking in molecules and directly impacts their chemical bonds. Alongside theoretical approaches, computational methods play an essential role in characterizing the electronic structures of molecular systems. The Chemical Bond Overlap Software (ChemBOS) is a program dedicated to the analysis of chemical bonds using the OP/TOP method. This work evaluates recent implementations focused on handling MCSCF wavefunctions and enhances the topological analysis of overlap density in ChemBOS. To test these implementations, the ions [Cr(OH2)6] 3+, Cr(OH2)6] 2+, [Fe(CN)6] 4− and [Fe(CN)6] 3− were analyzed, as there is experimental evidence of the JT effect in Cr(II) and Fe(III) complexes. Their wavefunctions were processed using Density Functional Theory (DFT) and Complete Active Space Self-Consistent Field (CASSCF) methods with the ORCA program. Chemical bonds were analyzed using the OP/TOP methodologies in ChemBOS and the Quantum Theory of Atoms in Molecules (QTAIM) in the MultiWFN program. The results indicate that the OP/TOP descriptors track the changes in the systems, both in the significant elongation of the Cr(II) complex and the slight contraction of the Fe(III) bonds. Additionally, this work introduces a new module for visualizing overlap density, the Overlap Density Viewer This module facilitates the visualization of density maps and provides a shorter execution time compared to other programs. Tests were conducted on densities obtained in other studies beyond those considered in this work, ensuring the Overlap Density Viewer’s functionality across different chemical systems. The results highlight the efficiency of the OP/TOP model in handling MCSCF wavefunctions of systems distorted by the JT effect, while also introducing a new tool for overlap density visualization integrated into ChemBOS.