This study is based on the valuation of a few model molecules. The objective of this research is focussed on the nonlinear optical (NLO) improvement of four organometallic molecules and one organic molecule. These molecules have been subjected to several calculations by different functionals: CAM–B3LYP, LC–BLYP, LC–wPBE, wB97X, M11, M06–2X, M08–HX and M08–SO. These functionals gave three orders of classification of the βtot parameters. The CAM–B3LYP functional recorded very good agreement between βtot parameters and gaps (ΔEH−L). Significant first hyperpolarizabilities (βtot) have been obtained around 880 * 10−30esu. The mechanisms of intramolecular charge transfer (ICT) have shown energetic passages from donor groups to acceptors and vice versa. The substitution of metals influences the location of π electrons at the level of the chromophores. Finally, the lengthening of the aromatic chains between the acceptor and donor groups shows significant NLO improvements. The first and second hyperpolarizabilities (βtot) and (γtot) for a chain of several benzene rings are of the order of 21,663.16 * 10−30esu and 16,464.65 * 10−35esu, respectively.
