Dipole and quadrupole (hyper)polarizability for the asymmetric stretching of carbon dioxide: Improved agreement between theory and experiment

We report a theoretical investigation of electric multipole moments and the dipole and quadrupole (hyper)polarizability for the asymmetric stretching of carbon dioxide. The dependence of the properties on the displacement parameter ΔR is not uniform. At the CCSD(T) level of theory the dipole moment varies around the equilibrium position asμ(ΔR)/ea0=-1.21ΔR+0.02ΔR3.At the MP2 level we find for the dipole-quadrupole polarizabilityAz,zz(ΔR)/e2a03Eh-1=23.6ΔR-1.2ΔR3,Ax,zx(ΔR)/e2a03Eh-1=17.7ΔR+0.9ΔR3.Our best value for the derivative dμdΔRe=-1.21e is in very good agreement with experiment. For the mean polarizability we obtain d2α¯dΔR2e=0.68e2a0Eh-1 which lifts the existing ambiguity for the respective experimental findings.