Electron affinities of d1 transition metal chloride clusters and onset of super halogen behavior

Geometry, electronic structure, and electron affinity of d1 transition metal chloride clusters (MCl$_{n}$, M = Sc,Y, La; n = 1--5) have been calculated using density functional theory. Chlorine atoms are chemically bound in all cases except for MCl$_{5}$. The electron affinities of MCl$_{n}$ (n = 1--3) are small and increase only marginally as a function of n until the valence of the metal atom is consumed. Beyond this, they rise sharply and reach a value of 5.96, 6.03 and 5.90 eV for ScCl$_{4}$, YCl$_{4}$ and LaCl$_{4}$, respectively and remain high for n = 5. MCl$_{n}$, (n = 4,5) clusters, therefore, behave as superhalogens. Results are compared with available experimental data