Electronic Structure of Actinyls: Orbital Properties.

Area of Science:

• Quantum Chemistry
• Actinide Chemistry
• Relativistic Calculations

Background:

• Actinyl ions (UO2^2+, NpO2^2+, PuO2^2+) are crucial in actinide chemistry.
• Understanding orbital covalent character is key to predicting their chemical behavior.

Purpose of the Study:

• To perform a detailed analysis of orbital covalent character in actinyl ions.
• To investigate both ground and excited electronic configurations.
• To provide reliable estimates of covalency beyond standard population analyses.

Main Methods:

• Utilized fully relativistic, four-component Dirac-Coulomb Hartree-Fock calculations.
• Employed multiple measures beyond population analyses to quantify covalency.
• Examined initial (ground state) and excited electronic configurations.

Main Results:

• Demonstrated a surprising similarity in orbital covalent character across different actinyls and electronic states.
• Highlighted significant 5f covalent character in bonding and antibonding orbitals.
• Estimated the participation of actinide 6d orbitals in covalent bonding.

Conclusions:

• Orbital covalent character in actinyls is remarkably consistent across various states and ions.
• The findings are essential for many-body treatments of actinyl wave functions.
• Provides a deeper understanding of bonding in heavy actinide elements.