Stretching and breaking of chemical bonds, correlation of electrons, and radical properties of covalent species

TL;DR

This paper presents a method to quantitatively analyze chemical bond stretching and breaking by examining electron correlation and unpaired electrons, validated across various bond types.

Contribution

It introduces a novel approach using unrestricted Hartree-Fock and configuration interaction theory to describe bond dissociation and electron correlation.

Findings

Effective unpaired electrons correlate with bond dissociation.

Graphs of electron singularities describe bond stretching.

Method validated on diverse chemical bonds.

Abstract

Chemical bonds are considered in light of correlation of valence electrons that is strengthened when the bond is dissociated. In the framework of the unrestricted Hartree-Fock single-reference version of the configuration interaction theory, effectively unpaired electrons lay the foundation of the electron correlation measure in terms of total number of the electrons (molecular chemical susceptibility). graphs and their singularities with respect to the interatomic distance allow presenting a quantitative description of stretching and breaking of chemical bonds. The approach validity is demonstrated on a large number of bonds of different order and chemical composition.