Interatomic Coulombic decay widths of helium trimer: Ab initio calculations

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Interatomic Coulombic decay (ICD) is a key process in the relaxation of excited atomic and molecular systems.
• Helium trimers provide a fundamental model system for studying many-body effects in van der Waals clusters.

Purpose of the Study:

• To extensively compute and analyze interatomic Coulombic decay (ICD) widths in helium trimers.
• To investigate the influence of three-body effects on ICD processes.
• To identify novel decay mechanisms in metastable states.

Main Methods:

• Utilized a fully ab initio method based on Fano theory for resonance calculations.
• Employed algebraic diagrammatic construction for the one-particle Green's function to solve the many-electron problem.
• Developed and applied an advanced partitioning approach for configuration space.

Main Results:

• Presented total ICD decay widths for all relevant states of the helium trimer with one-site ionization and excitation.
• Analyzed partial decay widths, demonstrating significant three-body effects on relaxation transitions.
• Identified a previously unreported type of three-electron decay in metastable states.

Conclusions:

• The study provides a comprehensive theoretical treatment of ICD in helium trimers.
• Three-body effects play a crucial role in determining the nature of ICD processes.
• Novel decay pathways, including three-electron processes, have been discovered.