Orbital formulation for electronic-structure calculations with linear system-size scaling

A novel energy functional for total-energy and molecular-dynamics calculations is introduced, and proven to have the Kohn-Sham ground-state energy as its absolute minimum. The use of this functional within a localized orbital formulation leads to an algorithm for electronic structure calculations whose computational work load grows linearly with the system size. The foundations and accuracy of the approach and the performances of the algorithm are first discussed analytically and then illustrated with several numerical examples.