DO BOND FUNCTIONS HELP FOR THE CALCULATION OF ACCURATE BOND-ENERGIES

The bond energies of eight chemically bound diatomics are computed usi ng several basis sets with and without bond functions (BF). The bond e nergies obtained using the aug-cc-pVnZ+BF basis sets (with a correctio n for basis set superposition error, BSSE) tend to be slightly smaller that the results obtained using the aug-cc-pV(n+1)Z basis sets, but s lightly larger than the BSSE corrected aug-cc-pV(n+1)Z results. The au g-cc-pVDZ+BF and aug-cc-pVTZ+BF basis sets yield reasonable estimates of bond energies, but, in most cases, these results cannot be consider ed highly accurate. Extrapolation of the results obtained with basis s ets including bond functions appears to be inferior to the results obt ained by extrapolation using atom-centered basis sets. Therefore bond functions do not appear to offer a path for obtaining highly accurate results for chemically bound systems at a lower computational cost tha n atom centered basis sets. (C) 1998 American Institute of Physics.