Charge-Transfer Steps in Density Functional Theory from the Perspective of the Exact Electron Factorization

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Accurate description of molecular dissociation and charge transfer is essential in Density Functional Theory (DFT).
• Exact Kohn-Sham (KS) and Pauli potentials can exhibit step structures during dissociation.
• Understanding the origin of these steps is limited by solely analyzing KS orbital behavior.

Purpose of the Study:

• To explain the origin of step structures in exact Kohn-Sham and Pauli potentials during molecular dissociation.
• To provide a deeper understanding of how many-electron effects are represented in one-electron theories like DFT.
• To propose methods for approximating these potentials during dissociation.

Main Methods:

• Utilized the exact electron factorization (EEF) to map the many-electron problem to a one-electron problem.
• Analyzed a simple diatomic molecule model to illustrate the physical origins of potential steps.
• Developed two novel methods for approximating the potentials during dissociation.

Main Results:

• Demonstrated that potential steps are a consequence of spatial electron entanglement and charge transfer.
• Showed that the step height can be directly deduced from the charge transfer mechanism.
• Proposed two approximation methods for the potentials, one relating to dissociated system states and another to Born-Oppenheimer treatments.

Conclusions:

• The EEF provides a clear physical interpretation of DFT potentials, revealing that steps arise from electron entanglement and charge transfer.
• The proposed methods offer pathways to accurately model dissociation and charge transfer phenomena in DFT.
• This work enhances the understanding of how complex many-electron interactions are captured within simplified one-electron frameworks.