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The Zinc telluride (ZnTe) system presents appealing optoelectronic properties used in radiology as well as in the detection of terahertz radiation (THz). In this work, we report a theoretical investigation of the ground and excited states of ZnTe and its ions ZnTe+ and ZnTe- using different ab inito methods. The potential energy curves (PEC) are computed using the CASSCF/LANL2DZ and MRCI/LANL2DZ methods. These curves allow inferring the different spectroscopic constants such as the internuclear distance (Re), the harmonic vibration frequency (ωe), the rotation constant (Be) and the dissociation energy (De). Our results indicate that the electronic states of ZnTe and its ions converge to several lower dissociation limits. The existence of unstable and crossings states is due to the presence of rotational and spin–orbit interactions. The results obtained are compared to the existing experimental data and have generally shown a reasonable agreement. [ABSTRACT FROM AUTHOR]

Two-body and non-additive three-body interactions in the ionic OH−(H2O)2 cluster have been studied by ab initio and DFT approaches. As the ab initio methods, the supermolecule Møller–Plesset perturbation theory (MP2, MP3, MP4SDQ, MP4), the coupled-cluster method including single, double, and approximate triple excitations [CCSD(T)], and the symmetry-adapted perturbation theory (SAPT) were used. A special attention was paid to the convergence of these treatments with respect to their perturbation operators. For the DFT calculations, the supermolecule results obtained with two functionals B3LYP and B3PW91 were examined, together with SAPT/DFT Heitler–London-type first-order terms. Various geometries of the OH−(H2O)2 trimer were considered. For some structures derived from larger clusters, the water molecules are located either in the first or in the second solvation shell. The convergence of the MP series is strongly dependent on the relative stability of the system and is especially discussed. [Copyright &y& Elsevier]