DFT study of enhancement in nonlinear optical response of exohedrally and endohedrally alkaline earth metals (Be, Mg, Ca) doped adamanzane

In this study, density functional theory has been used to investigate the geometric, electronic, linear and nonlinear optical properties of exohedrally and endohedrally doped adamanzane M-1(26 adz)M-2 where (M-1 = M-2 = Be, Mg and Ca). The multiple doping rendered excess electrons to the system which resulted in increased HOMO energies and resultantly reduced HOMO-LUMO gap (from 8.85 eV to 4.87 eV). The significant changes in excitation energy and vertical ionization energy indicated the introduction of excess electrons to the system. The NBO analysis confirmed that both the dopants are electron donating moieties. The formation of new HOMOs were also evident from the density of state (DOS) analysis. The new complexes exhibited remarkable nonlinear optical response and maximum first hyperpolarizability (beta = 8.19 x 10(3) au) and second hyperpolarizability (gamma = 8.12 x 10(5) au) were observed for AM9. This nonlinear response enhanced significantly when materials were placed in the light of 1907 nm wavelength for determination of dynamic hyperpolarizabilities. The UV-Vis analysis confirmed the transparency of designed materials in deep UV region. The structural properties of new materials were also authenticated by IR-spectra. The exceptionally high nonlinear response makes these materials desirable candidates for photonic, telecommunication and laser applications.