High-quality interatomic potential for Li+ center dot He

CCSD(T)/aug-cc-pVQZ and CCSD(T)/aug-cc-pV5Z methods have been employed to o btain accurate interatomic potentials for Li+ . He, from which spectroscopi c parameters are, derived. A potential is presented using the larger basis set consisting of 91 points (R greater than or equal to 1.3 Angstrom). An a ccurate value for the long-range D-4 parameter could be obtained from the p otential, but it was not possible to extract higher D-n terms. Since accura te values for D-n (n = 4, 6, 7 and 8) could be derived from literature data , these parameters were fixed (and damped), allowing the short-range potent ial to be fitted accurately to a Born-Mayer potential. (C) 2001 Elsevier Sc ience B.V. All rights reserved.