Multicomponent density functional theory embedding formulation.

Area of Science:

• Quantum Chemistry
• Computational Chemistry
• Density Functional Theory

Background:

• Multicomponent density functional theory (DFT) methods treat multiple particle types quantum mechanically.
• The nuclear-electronic orbital (NEO) approach handles electrons and select nuclei (protons) quantum mechanically.
• Existing NEO methods use electron-proton correlation functionals with standard electronic functionals.

Purpose of the Study:

• Develop a general theory for multicomponent embedded DFT for larger systems.
• Enable accurate treatment of electron-proton correlation in complex molecules.
• Introduce a novel DFT-in-DFT embedding scheme.

Main Methods:

• Separated total electronic density into regular and special subsystems.
• Applied different electron-proton correlation functionals to these subsystems.
• Defined special electron density using localized Kohn-Sham orbitals for localized correlation treatment.

Main Results:

• The proposed scheme accurately captures essential local electron-proton correlation.
• Applied to HCN and FHF(-) molecules, yielding qualitatively accurate nuclear densities.
• Demonstrated computational tractability for larger systems.

Conclusions:

• The multicomponent DFT-in-DFT embedding theory offers an accurate and efficient approach for quantum mechanical calculations.
• The method successfully treats electron-proton correlation effects.
• The general theory is adaptable to other partitioning schemes in multicomponent systems.