Understanding the kinetics during the metal-insulator transition process is crucial to sort out the underlying physical nature of electron-lattice interactions in correlated materials. Here, based on the temperature-dependent in situ x-ray absorption fine structure measurement and density-functional theory calculations, we have revealed that the monoclinic-to-tetragonal phase transition of ${\mathrm{VO}}_2$ near the critical temperature is characterized by a sharp decrease of the twisting angle $\delta$ of the nearest V–V coordination. The ${\mathrm{VO}}_2$ metallization occurs in the intermediate monocliniclike structure with a large twist of V–V pairs when the $\delta$ angle is smaller than 1.4°. The correlation between structural kinetics and electronic structure points out that the structural rearrangement is a key factor to narrow the insulating band gap.

• Received 25 August 2010

DOI:https://doi.org/10.1103/PhysRevLett.105.226405