How to Choose a Better Box: Complex Absorbing Potential Optimization for Anionic Resonances.

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Theoretical Chemistry

Background:

• Electronic-structure calculations for temporary anion states rely on complex absorbing potentials (CAPs).
• CAP configuration, including coupling strength (η) and boundary geometry, critically impacts calculation accuracy.
• Current methods for optimizing CAPs are often ad hoc and may not find optimal configurations.

Purpose of the Study:

• To develop and validate an efficient optimization strategy for box-complex absorbing potentials (box-CAPs).
• To systematically survey two-dimensional parameter spaces for CO⁻ and N₂⁻ resonances.
• To identify optimal CAP configurations that minimize wave function reflections and perturbations.

Main Methods:

• High-resolution surveys of two-dimensional CAP parameter spaces (η, r⁰L).
• Utilized Gyamfi and Jagau's ξ error function for optimization.
• Employed a hierarchical optimization strategy: first minimizing ξ, then η, subject to the ξ constraint.

Main Results:

• Identified narrow parameter ranges yielding high-quality results (ξ ∼ 10⁻⁴-10⁻⁵) in CAP spaces.
• Demonstrated the effectiveness of the proposed hierarchical optimization strategy.
• Achieved low-error resonance descriptions with the weakest possible CAP strength.

Conclusions:

• Systematic optimization of CAPs is essential for accurate electronic-structure calculations of temporary anions.
• The proposed hierarchical optimization strategy provides an efficient and reliable method for finding optimal box-CAP configurations.
• This approach enables the stabilization of resonance states with minimized errors and computational cost.