BASIS-SET CONVERGENCE OF HIGHLY DEFECTED SITES IN AMORPHOUS-CARBON

A systematic first-principles pseudopotential plane-wave and linear co mbination of atomic orbitals basis-set convergence study has been perf ormed for a 64-atom amorphous ''tetrahedral'' carbon network (Drabold et al.). Converged results of the two methods are consistent with each other and indicate that when large, site-dependent bond-angle and bon d-length distortions are present, variational freedom within a basis-s et representation is crucial for an accurate representation of atomic forces. Minimal basis-set/non-self-consistent methods are not adequate for these systems, but are more applicable to systems with minimal si te-dependent, electron-density distortions.