Ultrafast Dynamics of Atomic Correlated Disordering in Photoexcited VO ₂

ABSTRACT Recent experiments suggest that atomic disordering dynamics are more universal than coherent processes in photoinduced phase transitions (PIPTs), yet their microscopic origin remains elusive. Using real‐time time‐dependent density functional theory (rt‐TDDFT), we reveal that at low photoexcitation, higher lattice temperatures accelerate disordering and reduce the phase transition threshold by thermally exciting phonons that randomize lattice vibrations in VO 2 . Beyond the threshold fluence, however, the timescale and degree of disordering become temperature‐independent due to similar non‐uniform distributions of photoexcited holes across different temperatures. We further uncover anisotropic disordering: photoexcitation first elongates V─V dimers, followed by O‐mediated rotations with correlated displacements along z ‐axis. This correlated motion constrains disordering along z ‐axis, while disorder along x ‐axis remains more pronounced — a process we term “correlated disorder”. The correlated dynamic drives a transient monoclinic metallic phase, characterized by V‐atom motion primarily along x ‐axis. These findings establish a microscopic framework for anisotropic disordering pathways in VO 2 and provide new insights into disordered PIPT mechanisms.