Fractional Charge Density Functional Theory and Its Application to the Electro-inductive Effect

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Molecular Modeling

Background:

• The electro-inductive and vibrational Stark effects are crucial in understanding molecular interactions and properties.
• Fractional electrons have been theoretically implicated in these phenomena, but direct quantification remains challenging.

Purpose of the Study:

• To demonstrate the involvement of fractional electrons in electro-inductive and vibrational Stark effects.
• To introduce and validate a novel computational method for studying these effects in immobilized molecules.

Main Methods:

• Employed the chemical potential equalization principle to analyze electron behavior.
• Introduced fractional charge density functional theory (FC-DFT) as a canonical ensemble approach for open systems.
• Implemented the Perdew-Parr-Levy-Balduz (PPLB) condition via linear interpolation (LI-FC-DFT) to correct for delocalization errors.

Main Results:

• Fractional electrons are confirmed to be involved in both electro-inductive and vibrational Stark effects.
• Frontier molecular orbitals of immobilized molecules offer significant insights into these electronic effects.
• LI-FC-DFT calculations accurately predict experimental trends in molecular reactivity and frequency changes.

Conclusions:

• Fractional charge density functional theory, particularly with the LI-FC-DFT correction, provides a robust framework for studying electronic effects involving fractional electrons.
• The method offers a computationally accessible yet accurate approach to understanding molecular behavior in condensed phases and chemical reactions.