Thermally driven structural phase transition in SnSe monolayers in the NVT ensemble

SnSe monolayers undergo a thermally driven two dimensional (2D) structural phase transition^1-3 that results in a sudden change of lattice parameters that is consistent with experimental findings⁴. On another theoretical work, a different transition on a system with fixed walls (hence on an NVT ensemble) has been discussed. Here, we show that the phenomena on that other theory can be understood in terms of Car-Parrinello molecular dynamics (MD) calculations based on the NVT (constant number of atoms, volume, and temperature) ensemble. The present results thus contribute to a unified theoretical account to understand 2D structural transitions in these materials.

References:
¹ M. Mehboudi et al., Nano Lett. 16, 1704 (2016).
² M. Mehboudi, et al., Phys. Rev. Lett. 117, 246802 (2016).
³ S. Barraza-Lopez, et al., arXiv:1709.04581 (2017).
⁴ Chang, K. et al., Science 353, 274-278 (2016).