THEORETICAL CHARACTERS OF MgX (X = Te, Se, S AND O) CLUSTERS

Abstract

At DFT/B3LYP/LANL2DZ theoretical level, a series of MgX clusters with Mg3X3 hexagon, Mg4X4-t tetrahedron and Mg4X4-o octagon conformations are investigated. Their wavelengths of absorption spectra are calculated with time-dependent Density Functional Theory (TDDFT) using water as solvent. Firstly, the lowest vibrational frequencies, bond lengths, Dipole Moment and Raman spectra of them present regular change. Dipole Moment result shows that different clusters have different charges. From Raman spectra, we have discovered that they correlate with the conformation and variety of clusters. Conformations of MgO clusters have different optimizing characters with MgS , MgSe and MgTe molecules. Secondly, through Molecular Orbital and Nature Bond Orbital (NBO) analysis, we have found that all these clusters are materials with wider gaps. MgTe structures have stronger bonding. Besides, MgO have different transition from the other clusters. The order of wavelengths of absorption spectra is MgTe > MgSe > MgS . In a word, except MgO molecules, these clusters have similar or regular characters. These results are significant for experimental study of MgX nanocrystals.