Polarizabilities of confined two-electron systems:: the 2-electron quantum dot, the hydrogen anion, the helium atom and the lithium cation

The static dipole polarizabilities of two-electron systems confined by a spherical harmonic-oscillator potential omega have been calculated by the coupled-cluster CCSD method. The combined effect of the confining potential omega and the central electrostatic field on the polarizabilities of the quantum dot, and the confined systems, H-, He and Li+, respectively, have been investigated. The polarizabilities of the quantum dot can be calculated analytically. The polarizability alpha of the 2-electron quantum dot for omega=0.01 is calculated to be 19996 au, in perfect agreement with the exact value, 20000 au. Already medium confinement, omega=1.0, reduces alpha to 2.00 au. The decrease of the polarizability is smaller for H (-) (alpha=216.1 au for omega=0.0 and 0.985 au for omega=1.0), and much smaller for He and Li+ ( 1.3819 and 0.3813 au for He for omega=0.0 and omega=1.0, respectively, and 0.1921 and 0.128 au for Li+). The theoretical polarizabilities for unconfined (omega=0.0) H-, He and the Li+ cation are in very good agreement with the best published theoretical and/or experimental data. Our final polarizability for H-, 216: 0 +/- 0: 5 au, appears to be one of the most accurate values published so far. The optimization procedures of basis sets applicable to calculations of polarizabilities of systems confined by a spherical harmonic-oscillator potential are presented.