Calcium coated B80 fullerene: A study on various coating configurations of B80

We investigate the adsorption of calcium atoms on the surface of novel boron fullerenes and the α-boron sheet using an all electron density functional method within the generalized gradient approximation. Recent theoretical works show that the B80 fullerene coated with one Ca atom on each pentagonal ring is capable of storing up to 60 H2 molecules, yielding a gravimetric density of 8.2 wt.%. We have performed a detailed investigation of Ca adsorption on the B80 fullerene. At variance with recent results, our calculations show that a single Ca atom prefers to occupy a hexagonal site rather than a pentagonal site. The calculations on Ca12B80, Ca20B80 and Ca32B80 indicate that Ca atoms prefer to uniformly coat the whole surface over selectively occupying the pentagonal or hexagonal sites.