A note on the electric multipole moments of carbon dioxide

We have obtained accurate values for the electric quadrupole (Θ) and hexadecapole moment (Φ) of carbon dioxide. A very large (19s14p8d6f1g) basis set consisting of 456 uncontracted Gaussian-type functions is thought to provide near-Hartree–Fock values for both properties, Θ = - 3.79 ea 0 2 and Φ = - 1.41 ea 0 4 . At the CCSD(T) level of theory a [8s5p4d2f] basis set yields ( d Θ / d R ) e = 1.26 ea 0 and ( d 2 Θ / d R 2 ) e = 2.71 e , ( d Φ / d R ) e = 24.5 ea 0 3 and ( d 2 Φ / d R 2 ) e = 76.6 ea 0 2 at the equilibrium bond length of Re = 2.192 a0. Our final estimate for the hexadecapole moment is Φ e = - 2.50 ± 0.05 ea 0 4 .