Systematic Study of Hard-Wall Confinement-Induced Effects on Atomic Electronic Structure.

Area of Science:

• Computational Physics and Chemistry
• Quantum Mechanics
• Atomic Physics

Background:

• Existing studies on confined atoms lack systematic approaches and robust numerical methods.
• Understanding atomic behavior under confinement is crucial for various physical and chemical phenomena.

Purpose of the Study:

• To conduct a methodical study of atoms (H-Xe) and their monocations in hard-wall confinement.
• To investigate the influence of confinement on atomic configurations, electron distribution, and ionization radii.
• To evaluate and propose improvements for density-based estimates of van der Waals radii.

Main Methods:

• Utilized the HelFEM program, employing the finite element method for accurate hard-wall potential implementation.
• Performed nonrelativistic density functional theory calculations with three approximations: PW92, PBE, and r2SCAN.
• Calculated properties for low-lying configurations, including spin-polarized and spin-restricted densities, across varying confinement boundaries.

Main Results:

• Density functional approximations showed excellent agreement, indicating robust findings independent of the chosen functional.
• Observed significant electron shifts, with valence s electrons disfavored and higher-lying d and f orbitals occupied under strong confinement.
• Computed ionization radii revealed substantial differences compared to previous studies, highlighting the importance of confinement effects.

Conclusions:

• Systematic numerical calculations confirm significant alterations in atomic structure and electronic properties due to hard-wall confinement.
• Spin-polarization effects are crucial for open-shell configurations in confined atoms.
• Proposed a refined density-based estimate for van der Waals radii, addressing deficiencies in current models.