Investigating tunnel and above-barrier ionization using complex-scaled coupled-cluster theory

Area of Science:

• Quantum Chemistry
• Atomic and Molecular Physics
• Computational Chemistry

Background:

• Studying resonances induced by static electric fields is crucial for understanding atomic and molecular behavior.
• Electron correlation significantly impacts ionization processes.

Purpose of the Study:

• To present the theory and implementation of the complex-scaled coupled-cluster method with singles and doubles excitations (cs-CCSD).
• To investigate static electric field-induced resonances and ionization rates.

Main Methods:

• Application of the complex-scaled coupled-cluster method (cs-CCSD).
• Calculation of Stark shifts and ionization rates from complex energy.
• Utilizing augmented standard Gaussian basis sets.

Main Results:

• Accurate strong-field ionization rates obtained over six orders of magnitude.
• Characterization of field-induced resonances, including dipole moments and Dyson orbitals.
• Distinction between tunneling and above-barrier ionization mechanisms.

Conclusions:

• The cs-CCSD method provides accurate ionization rates and resonance characterization.
• Electron correlation plays a vital role in ionization processes.
• The study clearly differentiates tunneling and above-barrier ionization mechanisms.