Ab Initio Dot Structures Beyond the Lewis Picture.

Area of Science:

• Quantum Chemistry
• Theoretical Chemistry
• Chemical Bonding Theory

Background:

• The Lewis model is a cornerstone of chemical understanding, explaining molecular stability and reactivity.
• Quantum mechanics describes molecular properties through the many-particle wave function (Ψ).
• Connecting computable quantum mechanical quantities to the Lewis model is crucial for deeper chemical insight.

Purpose of the Study:

• To systematically expand topological probability density analysis to molecules with multiple bonds and lone pairs.
• To investigate and understand novel electronic structures beyond the traditional Lewis picture.
• To develop a more predictive framework for chemical bonding.

Main Methods:

• Employed correlated Slater-Jastrow wave functions for analysis.
• Utilized topological probability density analysis of the wave function's probability density (|Ψ|²).
• Introduced spin-coupled electron motifs as fundamental electronic fragments.

Main Results:

• Obtained non-Lewis structures that differ from the conventional Lewis model.
• Observed blurred or non-existent boundaries between bonds and lone pairs in the new structures.
• Identified spin-coupled electron motifs as a natural outcome of the analysis, coinciding with Lewis pairs for single bonds.

Conclusions:

• The study presents novel ab initio structures with potential for enhanced predictive capability in chemistry.
• The findings challenge the universality of the Lewis electron pair concept, particularly for multiple bonds.
• Rationalized new structures by considering Coulomb forces and Pauli repulsion, suggesting a refined understanding of electron distribution.