Figure 3

Migration of B vacancy. (a) The migration barriers for B-vacancy as a function of pressure for three different pathways. Boron vacancies are indicated by red circles, and the arrows represent their moving directions. (b) The fluctuations of potential energy and density during first-principles molecular dynamics (MD) simulations plotted for the hex-B2/9 allotrope at 50 GPa and 1500 K. The vertical dotted line represents the simulation time when a structural transition occurs from hex-B2/9 to hex-B1/8 during constant pressure–temperature MD simulations.