Ab initio prediction of amorphous B84. 
To explore the possible existence of boron clusters without carbon analogs, we study B(84) cluster as a prototypical system by ab initio calculations.  Structures of several isomer forms of B(84) are optimized.  Among these isomers, a group of amorphous (disordered) structures are found to be the most stable.  Different from the high-symmetry isomers, the amorphous B(84) clusters are more stable than the fullerene B(80) in terms of cohesive energy per atom.  These amorphous structures can be distinguished from other high-symmetry structures experimentally via, for example, infrared spectra.  The radial and angular distribution functions of amorphous B(84) structures are more diffuse than those of high-symmetry structures.  On the basis of these findings, we propose that amorphous structures may be generic for boron and dominate boron clusters in a range of cluster scale.