A density functional theory calculation on lanthanide monosulfides

Density functional calculations have been performed on several lanthanide monosulfide molecules, LnS (Ln = La, Ce, Eu, Gd, Yb and Lu). In agreement with experimental data, our theoretical results suggest that some estimated data for LnS molecules should be revised. Compared with 5d¹4fⁿ (n = 0, 1, 7, 14) configurations of free Ln atom, 5d⁰4f^m (m = 7, 14) configurations resulted in lower dissociation energy and vibration frequency, as well as larger hardness of LnS molecules. The calculated lanthanide contraction of 0.1 Å for LnS molecules is consistent with the rigidity of Ln-S bond. With the effect of 5d⁰ and 5d¹ configurations, the binding behaviors of Ln-4f orbital were discussed in LnS molecules.