The electron localization as the information content of the conditional pair density

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Understanding electron localization is crucial for predicting chemical properties and reactivity.
• Existing methods for quantifying electron localization can be computationally intensive or lack generality.

Purpose of the Study:

• To develop a novel, general descriptor for electron localization in atomic and molecular systems.
• To utilize information theory, specifically Kullback-Leibler divergence (DKL), to quantify electron localization.
• To establish a connection between electron localization and chemical structure.

Main Methods:

• Calculation of Kullback-Leibler divergence (DKL) between same-spin conditional pair probability density and marginal probability.
• Introduction of the electron localization descriptor χ = (N(σ) - 1) DKLfcut, accounting for electron density and system size.
• Application and testing of χ across various atomic and molecular systems.

Main Results:

• DKL serves as a robust measure of electron information gain, correlating with localized electron pairs.
• The descriptor χ successfully quantifies electron localization in diverse chemical environments.
• Computed χ values provide clear differentiation of electron localization, linked to electron number fluctuations.

Conclusions:

• The descriptor χ offers a successful and chemically intuitive explanation of electron structure.
• This approach provides a powerful tool for analyzing and visualizing electron localization in quantum chemical systems.
• The findings pave the way for deeper understanding of electron correlation and its impact on molecular properties.