Ab Initio and Density Functional Study on the First Hyperpo-larizabilities of Squaric Acid Homologues

【Abstract】 The first hyperpolarizabilities of four squaric acid homologues: squaric acid, 1,2-dithiosquaric acid, 1,2-diselenosquaric acid and 1,2-ditellurosquaric acid have been calculated using ab initio and DFT methods. The effects of equilibrium geometries, basis set and electron correlation on the first hyperpolarizabilties of these mole-cules were investigated. The frequency dispersion effect and solvent effect, which are essential to get reliable out-puts in comparison to the experimental results, have also been explored. On the basis of these investigations, it is worthy to point out that the heavy atom effect takes effect for these squaric acid homologues.更多还原