The 2D-to-3D geometry hopping in small boron clusters: The charge effect

DFT TPSSh/6-311+G(d) calculations are carried out on a series of 2D and 3D forms of Bn, n = 20, 22 and 24 in different charge states. For a certain size, the relative energy within a pair of two-dimensional quasi-planar (2D) and three-dimensional staggered double-ring (3D) boron cluster isomers may shift the sign as they reach a certain charge state. Specifically, electron addition tends to enhance the stability of the 2D over the corresponding 3D isomer irrespective of the available electrons. Linear correlations between 2D–3D relative energy and net charge are established. Along with 2D-to-3D geometry hopping at critical size, our results suggest a local 2D–3D geometry hopping via critical charge.