Borophene nanoclusters: Energetics and structures from analytical potentials

Boron shows a variety of properties, determining a chemistry rich and complementary to that of carbon, the neighbor atom in the Periodic Table. In this work, we investigated the strength and nature of the interaction involving B12 or B36 monomer, which represent molecular prototypes of borophene, the two-dimensional allotrope of elemental boron. For the representation of the intermolecular interaction, we developed new potential energy surfaces (PESs) that are based on accurate ab initio or density functional theory data. It is shown that borophene molecules are bound by weak intermolecular interactions of van der Waals nature, perturbed by antiaromatic effects. Moreover, the proposed PESs are given in an analytical form proper to investigate the structures and energetics of (B12)n and (B36)n clusters (with n = 2-10) by applying a global geometry optimization procedure. It is found that the most stable structures of (B12)n favor close contacts between the edges of the monomers, leading to cage-like clusters as n increases, and conversely, (B36)n clusters are mainly composed of stacked or herringbone structures. These results suggest the possibility to produce a novel class of two-dimensional borophene materials, exhibiting different features compared to graphene like structures, which could be of interest for the nanotechnology.