Finite temperature properties and phase transition behavior of quasi-planar B₃₆ nanocluster from first principles

Density-functional molecular dynamics simulations within the Car-Parrinello approach have been carried out to investigate the finite temperature properties and the thermal phase transition behavior of quasi-planar B₃₆ nanocluster via calculating a number of representative indicators such as root-mean-square bond length fluctuations, mean square displacement, radial distribution function, and total energy at forty equilibrium temperatures ranging from zero to 3200 K. Dramatic changes in the temperature dependence of these quantities take place from 1900 to 2200 K found as the phase transition region of the cluster. A detailed analysis of the total energy curve and mean square displacements of individual atoms within this melting region yields T _m ≃ 2125 K as the melting point. Results broadly support the view that the nanocluster preserves its hexagonal structure and quasi-planarity up to the phase transition region, exhibiting a high thermal stability by taking into account its ultra-small size and the melting point, which can be more increased in the case of nanostructures made of several B₃₆ units. (paper)