First, second and third order NLO response of alkaline earth metals doped C6O6Li6 organometallic complexes

Abstract

The geometric, electronic, linear and nonlinear (NLO) properties of pure C6O6Li6 and alkaline earth metals (AEM) doped C6O6Li6 organometallics are studied through quantum chemical methods. Interaction (Eint) and vertical ionization energies illustrate the thermodynamic and electronic stabilities of considered AEM@C6O6Li6 organometallic complexes, respectively. The highest interaction energy value is noticed for Ca@C6O6Li6 complex (–22.78 kcal/mol). After doping of alkaline earth metals, HOMO-LUMO energy gap (H-L Egap) is remarkably reduced. The variation in H-L Egap indicates the conductive properties of these complexes which occur due to transfer of electrons from the alkaline earth metals to the C6O6Li6 surface or vice versa. The electronic density shifting is also supported by natural bond orbital (NBO) charge and molecular orbitals analyses. UV–VIS analysis is used to confirm the electronic excitations. These organometallics show deep ultra-violet transparency below 200 nm which justifies their application in future laser devices. A noticeable NLO response is observed for these organometallics which is confirmed from the static first order hyperpolarizability (up to 1.90 × 104 au) and second order hyperpolarizability (up to 7.11 × 106 au) along with higher refractive index (up to 1.68 × 10−12 au) at 532 nm. The hyperpolarizability values are further enhanced at dynamic frequencies and these are increased up to 5.82 × 1010 au. These results illustrate the use of these organometallics in optical technologies for achieving better dc-Kerr effect and second harmonic generation effects.