Oxacarbon superalkali C3X3Y3 (X = O, S and Y = Li, Na, K) clusters as excess electron compounds for remarkable static and dynamic NLO response.

An intriguing class of excess electron oxacarbon superalkali clusters is explored for nonlinear optical response through density functional theory (DFT) methods at CAM-B3LYP/6-311++G(d,p). These superalkali clusters shows noticeable binding energies per atom (E) which reveals their thermodynamic stabilities (-86.45 ∼ -119.44 kcal mol). The obtained significant VIPs values also suggest the electronic stability of these clusters. The VIP values range from 2.06 eV to 3.42 eV. These clusters show remarkable electronic properties and their HOMO-LUMO gaps (E) are significantly reduced. The lowest H-L gap of 0.96 eV is obtained for COK while the highest H-L gap of 2.07 eV is calculated for CSLi. The obtained PDOS spectra further provide evidence for the superior electronic properties of these clusters. The clusters show excellent nonlinear optical properties as revealed from remarkable values (1.6 × 10 au) of static first hyperpolarizability. The controlling factors for hyperpolarizability are also explored by using conventional two-level model. The calculated values of β are correlated nicely with β. The crucial excitation energy is the key factor in controlling the first hyperpolarizability. In these excess electron clusters, the second hyperpolarizability (γ) response increases up to 4.3 × 10 au. Moreover, the calculated scattering hyperpolarizability (β) values are quite significant in these clusters and the highest value of 1.3 × 10 au is calculated for CSK. Additionally, these clusters also possess larger dynamic nonlinearities. The dynamic second hyperpolarizability with dc-Kerr effect increases up to 1.0 × 10 au. The remarkable values for refractive index (n) also suggest the excellent nonlinearity of these superalkali clusters.