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arXiv · 2606.14590

Lattice dynamics and the spectroscopic signatures of H-bond disorder in $δ$-AlOOH

Chenxing Luo·Sangjoon Lee·Hongjin Wang·Zhen Zhang·Renata Wentzcovitch
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Abstract

Raman and infrared anomalies associated with H-bond symmetrization in $δ$-AlOOH, including mode softening and linewidth broadening at 5-10 GPa, occur at significantly lower pressures than predicted by static harmonic theory. To resolve this discrepancy, we combine harmonic phonon calculations with strongly constrained and appropriately normed (SCAN)-based deep-potential molecular dynamics and phonon quasiparticle analysis at 300 K. This framework extracts temperature- and pressure-dependent frequencies and lifetimes from long-time trajectories, capturing the branch reorganization and rapid linewidth growth characteristic of the disordering regime. Incorporating quasiparticle renormalization and directional longitudinal-optical-transverse-optical (LO-TO) splitting further yields near-quantitative agreement with the ambient-pressure OH-stretching Raman multiplet. These results identify finite-temperature dynamical effects and the progressive loss of spectral coherence as the origin of the spectroscopic signatures of H-bond symmetrization.

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Chenxing Luo, Sangjoon Lee, Hongjin Wang, Zhen Zhang, Renata Wentzcovitch. 2026-06-12. Lattice dynamics and the spectroscopic signatures of H-bond disorder in $δ$-AlOOH. https://arxiv.org/abs/2606.14590

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