Heavy Atom Effect on the First Hyperpolarizabilities of Squaric Acid Homologues Studied by Ab Initio and DFT Methods

摘要

We have calculated the first hyperpolarizabilities of four squaric acid homologue molecules: 3,4-dithiohydroxy-3-cyclobutene-1,2-dione (OSSQ), 3,4-dithiohydroxy-3-cyclobutene-1, 2-dithione (SSSQ), 3,4-dithiohydroxy-3-cyclobutene-1,2-diselenone (SeSSQ) and 3,4-dithiohydroxy- 3-cyclobutene-1,2-ditellurone (TeSSQ). The correlation effect was investigated at the second-order Mφller-Plesset (MP2) perturbation and density functional theory (DFT) levels. The frequency disper- sion and solvent effect were considered to compare the theoretical values with the experimental observations. Based on all of these studies, it is worthy to point out that the heavy atom effect dis- covered for furan homologues is an influence on the first hyperpolarizabilities of squaric acid homologues.