Temperature-Dependent Lattice Dynamics and Vibration Effects in Cs₂UCl₆: Insights from DFT and Machine Learning...

Area of Science:

• Materials Science
• Solid State Physics
• Computational Chemistry

Background:

• Uranium-based materials are promising scintillators for precise detectors due to high stopping power.
• Understanding the excited-state lattice dynamics of uranium compounds is crucial but remains limited.

Purpose of the Study:

• Investigate the lattice dynamics of Cesium hexachlorouranate (Cs2UCl6).
• Elucidate the influence of octahedral vibrations and structural distortions on spectral properties.

Main Methods:

• Employed density functional theory (DFT) for fundamental calculations.
• Utilized machine learning (ML) to analyze complex interactions and predict behavior.
• Analyzed vibrational frequencies and temperature sensitivity of [UCl6]4- complex.

Main Results:

• Identified distinct frequency domains for [UCl6]4- and Cs interactions.
• Observed high temperature sensitivity in asymmetric stretching (ω0) and bending (ω1) vibrations.
• ML analysis revealed nonlinear synergistic effects and potential energy surface oscillations due to bond angle disorder.

Conclusions:

• Phonon scattering in Cs2UCl6 is linked to [UCl6]4- complex distortion from asymmetric bending vibrations.
• Findings provide theoretical insights into lattice dynamics and spectral regulation for uranium scintillators.