A computational probe for molecular environments

• Autor(a) principal: Paulo Fernando Gomes Velloso
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/57903
• topic: Isotopic probe; Molecular interactions; Molecular physics; Quantum chemistry; Molecular electrostatic fields; Molecular electrostatic potential; Post Born-Oppenheimer; Molecular environments; Física molecular; Campo eletrostático; Físico-química; Química quântica

In this thesis we report the use of an HD-like virtual molecule used as a probe to study molecular environments. The probe has a dipole moment which is tuned by modifying its nuclear masses using FNMC. It can be used to analyse molecular environments, in particular to probe polarisable molecular regions and to calculate molecular electrostatic fields, which we propose to be used as a new metric of intermolecular bond intensity. To test the probe we used simple systems (hydrogen, water, benzene and chlorobenzene). Once the performance of the probe was assessed, we applied it to analyse the cavity inside a frustrated Lewis pair and contribute to the discussion of the mechanism for hydrogen activation. Our results are in concordance with the electron transfer activation mecha- nism. We later applied the method to study two types of inter molecular interactions, π- and σ-hole bonds. These interactions are created by regions of positive electrostatic potential in molecules, capable of producing non-covalent interactions with negative re- gions, for example, lone pairs of molecules containing nitrogen or oxygen. Based on the Hellmann-Feynman theorem, which states that intermolecular bonds are fully described by Coulombian interactions (electrostatic plus polarisation), we used the probe to calcu- late the electric fields of the bonds and use it as a quantifier for the interactions.