Route to Chemical Accuracy for Computational Uranium Thermochemistry

Area of Science:

• Quantum Chemistry
• Relativistic Calculations
• Atomic and Molecular Physics

Background:

• Uranium compounds exhibit complex electronic structures due to relativistic effects.
• Accurate theoretical predictions are crucial for understanding uranium chemistry.

Purpose of the Study:

• To perform benchmark relativistic coupled-cluster calculations for uranium atom, UO, and UO2.
• To determine ionization and bond dissociation energies for these species.
• To assess the accuracy of the spinor-based quantum chemical approach.

Main Methods:

• Spinor-based relativistic coupled-cluster (CC) calculations.
• Analysis of relativistic, electron-correlation, and basis-set effects.
• Comparison of computed results with experimental data.

Main Results:

• Calculations provide accurate ionization energies for uranium atom, UO, and UO2.
• Accurate bond dissociation energies for UO and UO2 were determined.
• Demonstrated intrinsic convergence and favorable agreement with experimental values.

Conclusions:

• Spinor-based quantum chemical methods are uniquely applicable to open-shell uranium species.
• The method is effective for uranium oxidation states from U(0) to U(V).
• Validated the accuracy of relativistic, electron-correlation, and basis-set treatments in these calculations.