Dynamic dipole polarizabilities and C6 dispersion coefficients for small clusters of beryllium Ben (n=2,3,4)

Dipole polarizabilities (α), first (β) and second (γ) hyperpolarizabilities are obtained for small clusters of beryllium Ben (n=2,3,4) in a systematic study of basis set effects from CPHF calculations. In all cases, our static results are new and serve as a benchmark for future calculations. Electron correlation obtained at the MRDCI, MP4SDQ(T) and CCSD(T) levels reduces significantly the magnitude of the mean dipole polarizability of both clusters. Dynamic dipole polarizabilities calculated using TDGI method are given for a range of real (ω=0–0.2 a.u.) and imaginary frequencies (ω=0–4 a.u.). Corresponding isotropic and anisotropic dispersion coefficients between these clusters are also reported.