Bond order potentials: a study of s- and sp-valent systems

The relative structural stability of s- and sp-valent systems is examined within the fourth-moment approximation to the recently derived tight binding bond order potentials. At this low level of approximation the authors find that the application of a sum rule constraint to the choice of terminator is necessary to get good results. In particular, the competition between graphite, diamond and simple cubic sp-valent lattices is modelled well by the new angularly dependent bond order potentials.