Density functional calculations with simulated annealing – clusters and amorphous materials

The calculation of the structure of any material requires a method that (a) determines the total energy of the system of electrons and ions as a function of geometry and (b) avoids local minima in the energy surface that are energetically unfavourable. We review the problems inherent in such a strategy. The combination of the density functional (DF) formalism with finite-temperature molecular dynamics (MD) techniques provides a scheme that addresses both problems. We demonstrate its value in two areas: (1) Structures of small clusters of phosphorus, (2) The structures of liquid and amorphous selenium and of amorphous phosphorus.