First-principles Newns-Anderson Hamiltonian construction for chemisorbed hydrogen at metal surfaces

Area of Science:

• Surface Science
• Computational Chemistry
• Materials Science

Background:

• The Newns-Anderson Hamiltonian is crucial for modeling gas-solid interface adsorption.
• Its traditional construction involves simplifying assumptions like constant coupling and wideband limit approximation.
• These assumptions can limit accuracy in describing chemisorption dynamics.

Purpose of the Study:

• To develop a first-principles method for constructing Newns-Anderson Hamiltonians.
• To apply this method to hydrogen chemisorption on Al, Cu, and Pt (111) surfaces.
• To validate the accuracy of the constructed Hamiltonians and assess common approximations.

Main Methods:

• Utilized projection operator diabatization on Kohn-Sham density functional theory (DFT) derived Hamiltonian matrices.
• Calculated projected density of states, electronic tunneling lifetimes, and vibrational lifetimes.
• Analyzed the chemisorption function to evaluate the wideband limit approximation.

Main Results:

• Successfully constructed Newns-Anderson Hamiltonians for H/Al(111), H/Cu(111), and H/Pt(111).
• Computed properties showed good agreement with reference calculations, validating the electronic coupling.
• The wideband limit approximation was found valid for H/Al(111) but limited for H/Cu(111) and H/Pt(111).

Conclusions:

• The first-principles approach provides a more accurate construction of Newns-Anderson Hamiltonians.
• This method enhances the study of hydrogen chemisorption on metal surfaces.
• The findings highlight the limitations of the wideband limit approximation for certain metal-adsorbate systems.