Frozen-core full-CI calculation of imaginary frequency-dependent dipole polarizabilities of ground state BeH2 and the C6 dispersion coefficients of its homodimer

Frozen-core full-CI calculations of frequency-dependent dipole polarizabilities (FDPs) of ground state BeH2 at the experimental distance of R = 2.506a0 have been performed using an extended set of 208 contracted GTO functions [9s9p5d3f] on Be and [9s8p6d] on H involving about 58 × 106 symmetry-adapted Slater determinants. The Casimir–Polder integral was then evaluated analytically using eight optimized imaginary frequencies chosen according to a recently developed interpolation technique which allows for the evaluation of the three dipole dispersion constants for the BeH2–BeH2 homodimer, from which isotropic C6 and anisotropy γ6 coefficients are derived for the first time.