Electric quadrupole moment and quadrupole polarizability of the copper dimer from high level ab initio and some density functional theory calculations

Abstract

We have employed flexible, purpose-oriented, molecule-specific basis sets to calculate the electric multipole moments and quadrupole polarizability of the copper dimer with ab initio and some density functional theory methods. At the CCSD(T)/[9s8p7d1f] level of theory the quadrupole moment and mean quadrupole polarizability vary around the experimental bond length (Re=2.2197Å) as [Θ(R)-Θ(Re)]/ea02=1.07(R-Re)-0.55(R-Re)2+0.15(R-Re)3-0.08(R-Re)4[C¯(R)-C¯(Re)]/e2a04Eh-1=224.9(R-Re)+51.5(R-Re)2+6.8(R-Re)3+6.1(R-Re)4with −0.4 ⩽ (R−Re)/Å ⩽ 0.4.A discrepancy is observed between ab initio and density functional theory methods in the calculation of the quadrupole moment while the two classes of methods are seen to be in fair agreement as regards the calculation of the hexadecapole moment and the quadrupole polarizability.