DFT studies on nonlinear optical properties of neutral nest-shaped heterothiometallic [MOS 3Py 5Cu 3X] (M = Mo, W; X = F, Cl, Br, I) clusters

Abstract

Theoretical calculations were carried out on some neutral nest-shaped heterothiometallic cluster compounds [MOS 3Py 5Cu 3X] (M = Mo, W; X = F, Cl, Br, I) with the high first static hyperpolarizabilities β values. The geometries of these cluster compounds were optimized by the restricted DFT method at B3LYP level with LanL2DZ base set without any constrains. In order to understand the relationship between the first static hyperpolarizabilities and the compositions of these clusters, the frontier orbital compositions and energy gaps between the HOMO and LUMO orbitals were calculated and analysed. In these clusters the HOMO orbitals are mainly composed of halogen atoms and the first static hyperpolarizability increases from F to I atom. The LUMO orbitals of clusters [MoOS 3Py 5Cu 3X] are comprised of Mo, O and S atoms while the LUMO orbitals of clusters [WOS 3Py 5Cu 3X] composed of W atom and pyridine ring. The energy gaps between the HOMO and LUMO orbitals of the clusters [MoOS 3Py 5Cu 3X] are smaller than those of the clusters [WOS 3Py 5Cu 3X]. As a result the first static hyperpolarizability values of the clusters [MoOS 3Py 5Cu 3X] are higher than those of the clusters [WOS 3Py 5Cu 3X].