Ab initio determination of the electric multipole moments and static (hyper)polarizability of HCCX, X = F, Cl, Br, and I.

We report electric multipole moments and (hyper)polarizabilities for the haloethynes HCCX, X = F, Cl, Br, and I. The molecular properties have been obtained from finite-field self-consistent field, Møller-Plesset perturbation theory and coupled cluster calculations with large, carefully optimized basis sets of gaussian-type functions. The mean dipole (hyper)polarizability and the mean quadrupole polarizability near the Hartree-Fock limit are alpha/e(2)a(0) (2)E(h) (-1) = 23.74 (HCCF), 37.26 (HCCCl), 43.97 (HCCBr), 56.44 (HCCI), beta/e(3)a(0) (3)E(h) (-2) = -73.9 (HCCF), -67.0 (HCCCl), -39.5 (HCCBr), 42.7 (HCCI), gamma/e(4)a(0) (4)E(h) (-3) = 4,914 (HCCF), 6,554 (HCCCl), 9,328 (HCCBr), 14,949 (HCCI), and C/e(2)a(0) (4)E(h) (-1) = 160.3 (HCCF), 317.1 (HCCCl), 471.2 (HCCBr), 671.2 (HCCI). Electron correlation has a small effect on the dipole polarizability but affects strongly the hyperpolarizability. Agreement with the available experimental data is more or less fair for HCCF, HCCCl, and HCCBr but less satisfactory for HCCI.