Ab Initio Molecular Dynamics with Maximally Localized Wannier Functions

We present a novel formulation of ab initio molecular dynamics that should be useful to simulate insulating systems. In this scheme maximally localized Wannier functions instead of delocalized Bloch states evolve on the fly during nuclear dynamics. Localized Wannier orbitals offer several advantages over orbitals that are delocalized in the entire simulation cell. In fact, at variance with the latter, they provide a picture of the electronic bonds consistent with simple chemical intuition. In addition, by taking advantage of their exponential localization it should be possible to develop ab initio molecular dynamics schemes having a computational cost that scales linearly rather than cubically with system size. We show that maximally localized Wannier functions can be calculated efficiently within Car-Parrinello dynamics and use water in gas and liquid phase as a test system to demonstrate our scheme and illustrate its usefulness.