Computing Decay Widths of Autoionizing Rydberg States with Complex-Variable Coupled-Cluster Theory.

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics
• Computational Spectroscopy

Background:

• Rydberg states are highly excited atomic and molecular states.
• Understanding their autoionization widths is crucial for spectroscopy and reaction dynamics.
• Previous methods faced limitations with complex basis sets for Rydberg states.

Purpose of the Study:

• To compute autoionization widths of Rydberg states in neon and N2.
• To introduce and validate a new computational protocol for complex-variable methods applied to Gaussian basis sets.
• To investigate the trends of decay widths with respect to quantum numbers.

Main Methods:

• Equation-of-motion coupled-cluster theory.
• Complex scaling and complex basis functions.
• A novel computational protocol utilizing Kaufmann basis functions.

Main Results:

• Successfully applied complex-variable methods to Rydberg states in Gaussian basis sets for the first time.
• Calculated autoionization widths for specific Rydberg states of neon (3s, 3p, 4p, 3d).
• Determined widths for N2 Rydberg states (3sσ, 3dσ, 3dπ) of the Hopfield series.
• Observed a decrease in decay width with increasing angular momentum and principal quantum number.

Conclusions:

• The new computational protocol is effective for studying atomic and molecular Rydberg states.
• The observed trend in decay widths provides insights into the stability of these excited states.
• This work advances the computational treatment of autoionization phenomena in quantum systems.