The structure of selenium clusters - Se₃ TO Se₈

The equilibrium geometries of selenium clusters Se₃ to Se₈ have been calculated. The total energy is determined for each geometry using a parameter-free density functional method, and the most prominent low-energy structures are found using combined molecular dynamics and simulated annealing techniques. This procedure is shown to provide a powerful tool for locating the most important minima on complicated energy surfaces. For Se₆ and Se₈ the calculated geometries agree very well with the measured geometries in the crystalline state, and we predict the geometries of the others. Virtually identical geometries are obtained for local and non-local pseudopotentials.