Stability of "No-Pair Ferromagnetic" Lithium Clusters

Area of Science:

• Quantum Chemistry
• Materials Science
• Computational Physics

Background:

• High-spin lithium clusters (Li_n, n=2-21) exhibit unique electronic properties.
• These clusters are stable despite the absence of conventional bonding electron pairs.

Purpose of the Study:

• To systematically investigate the stability and electronic structure of high-spin lithium clusters.
• To benchmark various density functional theory (DFT) functionals for describing these systems.
• To identify the most accurate DFT functional for high-spin lithium cluster research.

Main Methods:

• Systematic study using density functional theory (DFT).
• Benchmarking of 42 DFT functionals against CCSD(T)/cc-pVQZ reference data for small clusters (n=2-6).
• Many-body energy decomposition analysis to understand binding energy contributions.
• Analysis of the second energy difference to predict cluster stability.

Main Results:

• High-spin lithium clusters demonstrate stability relative to isolated atoms.
• Strong non-additivity in binding energies is primarily governed by three- and four-body contributions.
• The LC-BP86 DFT functional was identified as the most accurate for describing these clusters.
• A method to predict higher-stability clusters based on energy differences was developed.

Conclusions:

• The LC-BP86 functional provides a reliable description for high-spin lithium clusters.
• Understanding many-body effects is crucial for accurate binding energy calculations.
• The study offers a pathway for predicting stable lithium cluster configurations.