Consistent density functional theory-based description of ion hydration through density-corrected many-body...

Area of Science:

• Computational chemistry
• Theoretical chemistry
• Materials science

Background:

• Density functional theory (DFT) methods often struggle with delocalization errors, limiting accuracy in describing molecular interactions, particularly in ion-water systems.
• The SCAN functional, while promising, is susceptible to these errors, impacting its predictive power for hydrated ions.

Purpose of the Study:

• To investigate the impact of delocalization error on the SCAN functional in modeling ion-water and water-water interactions.
• To evaluate the performance of density-corrected SCAN (DC-SCAN) for hydrated ions (Na+ and Cl- in water).
• To assess the applicability of DC-SCAN for condensed-phase simulations.

Main Methods:

• Calculated ion-water and water-water interaction energies using the SCAN and density-corrected SCAN (DC-SCAN) functionals.
• Employed density-corrected many-body SCAN (MB-SCAN(DC)) potentials derived from the many-body expansion.
• Performed molecular dynamics simulations at ambient conditions.

Main Results:

• DC-SCAN significantly improves the accuracy of predicting n-body and interaction energies, approaching coupled cluster theory levels.
• DC-SCAN demonstrates size-consistency, accurately describing interactions beyond the first solvation shell.
• MB-SCAN(DC) potentials accurately predict the solvation structure of Na+ and Cl- and reproduce liquid water structure.

Conclusions:

• Density correction effectively mitigates delocalization errors in SCAN, leading to highly accurate descriptions of ion hydration.
• The unified density-corrected many-body formalism shows significant promise for efficient and accurate DFT-based simulations of condensed-phase systems.
• This approach offers a pathway to achieve chemical accuracy in complex molecular simulations.