A comparative study of ab initio SCF-CI and DFT. Example of small boron clusters

A linear search for minima on potential energy surfaces based on analytical gradient methods and the determination of binding energies of small boron clusters Bn (n = 2–14) have been made using the ab initio Hartree-Fock and configuration interaction quantum chemical methods as well as by means of density functional theory at the local spin density and non-local corrections to the exchange-correlation levels of theory. The final Hartree-Fock optimized topologies of the neutral boron clusters are identical with those derived with the local spin density approximation. The most stable boron clusters have convex or quasi-planar structures. The convex clusters seem to be segments of the surface of a sphere. The capabilities of both methods for such cluster systems are illustrated.