Temperature-driven structural phase transitions in SmNiO₃: insights from deep potential molecular dynamics simulations

The metal-insulator transition (MIT) in rare-earth nickelates exemplifies the intricate interplay between electronic correlations and lattice dynamics in quantum materials. This work focuses on SmNiO₃ as a prototypical system, employing molecular dynamics simulations based on a "hidden" magnetic potential model. Our simulations reveal two key findings. First, the structural phase transition in SmNiO₃ is intrinsically temperature-driven and occurs spontaneously via collective lattice distortions. Moreover, systematic high-pressure simulations demonstrate a distinct pressure dependence of the transition temperature, which decreases monotonically with increasing external hydrostatic pressure. These results provide atomistic insights into the cooperative mechanisms underlying the MIT and the interplay between structural distortions and electron correlation effects. The computational approach developed herein offers a generalizable framework for investigating complex phase transitions in correlated quantum materials.