Dynamic dipole polarizabilities and C-6 dispersion coefficients for small clusters of beryllium Be-n (n = 2,3,4)

Dipole polarizabilities (alpha), first (beta) and second (gamma) hyperpolar izabilities are obtained for small clusters of beryllium Be, (n = 2,3,4) in a systematic study of basis set effects from CPHF calculations. In all cas es, our static results are new and serve as a benchmark for future calculat ions. Electron correlation obtained at the MRDCI, MP4SDQ(T) and CCSD(T) lev els reduces significantly the magnitude of the mean dipole polarizability o f both clusters. Dynamic dipole polarizabilities calculated using TDGI meth od are given for a range of real (omega = 0-0.2 a.u.) and imaginary frequen cies (omega = 0-4 a.u.). Corresponding isotropic and anisotropic dispersion coefficients between these clusters are also reported. (C) 1999 Elsevier S cience B.V. All rights reserved.