Role of Kinetic Exchange and Coulomb Interaction in Bonding of Hydrogen Molecular Systems and Excited States

TL;DR

This paper investigates the electronic structure and bonding in hydrogen molecules using the EDABI approach, emphasizing the roles of kinetic exchange and Coulomb interactions, and extends the analysis to excited states and dissociation limits.

Contribution

It introduces a comprehensive analysis of hydrogen bonding using the EDABI method, combining first- and second-quantization with exact solutions of the extended Heitler-London model.

Findings

Hydrogen molecules exhibit distinct bonding characteristics influenced by kinetic exchange and Coulomb interactions.

The neutral H2 molecule shows greater stability and covalency compared to ionic forms.

The EDABI approach effectively models excited states and dissociation processes in hydrogen systems.

Abstract

We present a detailed investigation of the electronic structure and bonding characteristics of hydrogen-based molecular systems (\ch{H2+}, \ch{H2}, \ch{H2-}) using the Exact Diagonalization Ab Initio (EDABI) approach within the framework of combined first- and second-quantization. By analyzing the relative contributions of kinetic exchange and effective Coulomb interactions, we provide a comprehensive understanding of covalency, atomicity, and ionicity as a function of interatomic distances. Our approach leverages exact solutions of the extended Heitler-London model to quantify these interactions, extending the analysis to the discussion of properties of excited states and the dissociation limit to these molecules. The findings reveal significant differences in bonding characteristics, particularly highlighting the stability and bonding nature of the neutral \ch{H2} molecule compared to its ionic counterparts. This study not only enhances an understanding of molecular interactions in hydrogen systems but also demonstrates the potential of the EDABI approach in developing more accurate computational models in quantum chemistry.