An ab Initio Prediction of the Extraordinary Static First Hyperpolarizability for the Electron-Solvated Cluster (FH)₂{e}(HF)

A theoretical prediction of the nonlinear optical (NLO) properties of the hydrogen fluoride trimer anion (FH) 2 {e}(HF) reveals that this electron-solvated cluster possesses exceptionally large static first hyperpolarizability. Using the d-aug-cc-pVDZ basis set supplemented with diffusive bond functions (BF), we obtained the mean static first hyperpolarizability (β 0 ) for (FH) 2 {e}(HF) and its neutral core (HF) 2 {}(HF) at the CISD level of theory. The β 0 is 8.1 × 10 6 au for (FH) 2 {e}(HF) and 5.1 au for (HF) 2 {}(HF). Obviously, the excess electron is the key factor in bringing to (FH) 2 {e}(HF) the significantly large NLO response. The other properties of (FH) 2 {e}(HF) are also much larger than those of its neutral core. The values of the static dipole moment, mean polarizability, and anisotropy of the polarizability are, respectively, μ = 1.5764 au, α 0 = 654.67 au, and Δα = 224.71 au for the anion, and μ = 0.9351 au, α 0 = 17.34 au, Δα = 5.40 au for the neutral core. In addition, the field dependences of the polarizability and first hyperpolarizability are obtained at the MP2/d-aug-cc-pVDZ+BF level of theory. And the influence of the secondary interaction, H-bond-excess electron attracting, on the static first hyperpolarizability of (HF) 2 {e}(HF) is also explored.