Dipole polarizability pseudospectra and C6 dispersion coefficients for two-electron model systems

Convergence of dipole pseudospectra for the 2-electron model systems He and H2 is studied for Riley-Dalgarno- and Kolos-Wolniewicz-type wavefunctions explicitly including electron correlation in terms of positive powers of the interelectronic distance. 40-term pseudospectra for He and 34-term for H2 give almost a 4-figure accuracy for the static polarizabilities of the monomers and the resulting C6 dispersion coefficients of the dimers.