Quantifying electron-correlation effects in small coinage-metal clusters via ab initio calculations

Area of Science:

• Computational chemistry
• Materials science
• Quantum mechanics

Background:

• Coinage metal clusters (Cu, Ag, Au) exhibit complex electronic behaviors.
• Understanding many-electron correlation is vital for predicting cluster properties.

Purpose of the Study:

• Investigate many-electron correlation effects in Cun, Agn, and Aun clusters (n=1-4).
• Quantify the impact of electron correlation on cluster stability and electronic structure.

Main Methods:

• Ab initio calculations using fixed-node diffusion Monte Carlo (FN-DMC).
• Density functional theory (DFT) and Hartree-Fock (HF) methods were employed.
• Comparison of FN-DMC and HF results to determine correlation energies.

Main Results:

• Accurate correlation energies were obtained for neutral and charged clusters.
• Calculated properties (bond lengths, binding energies, ionization potentials, electron affinities) agree well with experiments.
• Electron correlation is essential for cluster stability, contributing over 90% to binding energies in small copper clusters.
• Orbital-occupation dependence of correlation energy and electron pairing was demonstrated.

Conclusions:

• Electron correlation plays a critical role in the electronic structure and stability of coinage metal clusters.
• The study highlights the importance of advanced computational methods for accurately describing these systems.