Alternative forms and transferability of electron-proton correlation functionals in nuclear-electronic orbital...

Area of Science:

• Quantum chemistry
• Computational physics
• Materials science

Background:

• Multicomponent density functional theory (DFT) enables simultaneous quantum mechanical treatment of electrons and nuclei.
• The nuclear-electronic orbital (NEO) framework facilitates quantum treatment of specified protons alongside electrons.
• Recent advancements include the epc17 electron-proton correlation functional, derived from a multicomponent Colle-Salvetti formalism.

Purpose of the Study:

• To derive and evaluate a new electron-proton correlation functional, epc18.
• To assess the performance of epc18 and compare it with the existing epc17 functional.
• To investigate the transferability of these functionals with various electronic exchange-correlation functionals within the NEO-DFT framework.

Main Methods:

• Derivation of the epc18 electron-proton correlation functional using a modified functional parameter for correlation length.
• Implementation of epc18 within the nuclear-electronic orbital (NEO) framework.
• Testing and comparison of epc17 and epc18 for predicting 3D proton densities and proton affinities.

Main Results:

• The newly derived epc18 functional demonstrates performance comparable to the epc17 functional.
• Both epc17 and epc18 functionals show good transferability across a range of electronic exchange-correlation functionals.
• The study confirms that diverse electronic exchange-correlation functionals can be effectively combined with epc17 and epc18.

Conclusions:

• The epc18 functional offers a viable alternative for electron-proton correlation in NEO-DFT.
• The transferability of these functionals broadens their applicability in multicomponent quantum mechanical calculations.
• Further research into electron-proton correlation functional forms is crucial for advancing NEO-DFT.