Determination of the complete polarizability tensor of 1,3-butadiene by combination of refractive index and light scattering measurements and accurate quantum chemical ab initio calculations

We have combined accurate quantum chemical calculations and light scatterin g measurements to obtain a reliable estimate of the electric dipole polariz ability anisotropy of 1,3-butadiene. The theoretical investigation was base d on finite-field many-body perturbation theory and coupled cluster techniq ues. An extensive study of basis set, electron correlation, and molecular g eometry effects leads to a static value of alpha = 54.04 e(2)a(0)(2)E(h)(-1 ) for the mean dipole polarizability of trans-butadiene, in very good agree ment with the experimental result of 54.64 e(2)a(0)(2)E(h)(-1) obtained fro m an extrapolation to infinite wavelength of refractivity data [Hohm, U.; T rumper, U. Ber. Bunsenges. Phys. Chem. 1992, 96, 1061]. The measured value of the dipole polarizability anisotropy of trans-butadiene is 42.5(1.7) e(2 )a(0)(2)E(h)(-1) at 514.5 nm. To our knowledge, these are the first light-s cattering experiments to be reported for 1,3-butadiene. The present investi gation brings forth new possibilities for the extension of accurate determi nation of electric polarizabilities to molecules of some size, cis-Butadien e is less polarizable and less anisotropic than the trans isomer.