Quantal density functional theory of the hydrogen molecule

Area of Science:

• Quantum chemistry
• Theoretical chemistry
• Computational physics

Background:

• Traditional Kohn-Sham density functional theory (DFT) models interacting systems.
• Accurate modeling of electron correlations and many-body effects is crucial.

Purpose of the Study:

• To perform a quantal density functional theory (Q-DFT) study on the hydrogen molecule.
• To analyze the ground state properties using Q-DFT.

Main Methods:

• Utilized quantal density functional theory (Q-DFT).
• Transformed the interacting system into a non-interacting fermion system (S system).
• Employed the Kolos and Roothaan highly accurate correlated wave function for hydrogen.

Main Results:

• Q-DFT successfully obtains equivalent density, total energy, and ionization potential.
• Q-DFT describes the S system using classical fields and quantal sources representing many-body effects.
• Calculated energy components (Hartree, Pauli, Coulomb, correlation-kinetic) in virial form.

Conclusions:

• Q-DFT provides a robust framework for studying molecular systems.
• The highest occupied eigenvalue of the S system directly yields the ionization potential.
• Q-DFT effectively accounts for electron correlations, Coulomb repulsion, and kinetic effects.