High-quality interatomic potential for Li +·He

Abstract

CCSD(T)/aug-cc-pVQZ and CCSD(T)/aug-cc-pV5Z methods have been employed to obtain accurate interatomic potentials for Li +·He, from which spectroscopic parameters are derived. A potential is presented using the larger basis set consisting of 91 points ( R⩾1.3 Å). An accurate value for the long-range D 4 parameter could be obtained from the potential, but it was not possible to extract higher D n terms. Since accurate 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 potential to be fitted accurately to a Born–Mayer potential.