Polarizabilities and second hyperpolarizabilities of hydrogen chains using the Spin-component- scaled Moøller-plesset second-order method

Static longitudinal polarizabilities (a) and second hyperpolarizabilities (y) of model H₂ chains have been calculated at different ab initio levels to address the performance of the recently proposed spin-component-scaled MP2 (SCS-MP2) method (Grimme, J. Chem Phys 2003, 118, 9095). For both α and γ, the SCS-MP2 method improves over the MP2 results in comparison with reference values evaluated at the CCSD(T) level. Differences from the reference are in the range of 4-6% for α and 1-4% for γ. In the case of γ, the SCS-MP2 scheme improves not only over MP2 but also MP4 and CCSD. Further studies are needed on conjugated systems to evaluate the generality of these results.