Pair potentials for C-C, Si-Si and Si-C from inversion of the cohesive energy

The Carlsson-Gelatt-Ehrenreich inversion technique is applied to the derivation of pair potentials for the elemental bonds C-C and Si-Si, and the compound bond Si-C. Chen's Mobius function method is used to speed up the convergency. The cohesive energies are obtained from the ab initio pseudopotential total energy calculation of Chang and Cohen within the framework of the local-density approximation and fitted to the universal binding energy function of Rose et al. The pair potentials thus obtained reproduce exactly the full cohesive energy curves, lattice constants and bulk moduli.