Dynamic first hyperpolarizability of trans- and cis-isomers of azobenzene chromophore DO3 calculated at DFT and MP2 levels

Both static and dynamic molecular quadratic nonlinear-optical characteristics of trans- and cis-isomers of azo-chromophore Disperse Orange, DO3, are studied by correlated MP2 technique and TD-DFT with two density functionals: meta-GGA M06.2X and range-separated omega B97X ones. The effect of solvent and radiation frequency on the first hyperpolarizability values is considered. All the tendencies obtained at the MP2 level are found to be valid at DFT level, the first hyperpolarizability values estimated with M06.2X being quite close to those calculated at MP2 level. The solvent (chloroform) effect results in 3 times growth of the static first hyperpolarizability values for trans-isomer, and ca 2.5 times - for cis DO3. The effect of radiation frequency on the first hyperpolarizability values reveals the systematic decrease of the beta(tot) values with the decrease of frequency. The comparison of the first hyperpolarizability values for trans- and cis-isomers demonstrates the dominating value for trans-DO3, MP2 providing systematically larger ratio beta(tot) [trans]/beta(tot)[cis] than DFT; the estimations obtained by TD-DFT being in a very good agreement with the values presented in literature.