Toward Energy-conserving, Linear-scaling, Real Space Ab Initio Molecular Dynamics

Ian Dunn, Columbia University

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Born-Oppenheimer molecular dynamics (BOMD) calculates forces on nuclei via an iterative quantum-mechanical electronic optimization at each time step. A tight convergence of this optimization is typically required in order to prevent a systematic drift in the total energy over time. Using extended Lagrangian BOMD (XL-BOMD), where the initial guess to this optimization procedure is propagated alongside the nuclei, energy conservation can be achieved without requiring an expensive tightly converged electronic solution. We have adapted XL-BOMD for use with the scalable real-space BOMD algorithms developed by Fattebert and Osei-Kuffuor. The fusion of these two methods requires the propagation of both the initial guess for the Kohn-Sham subspace as well as the centers of localized electronic orbitals. XL-BOMD has shown remarkable energy conservation when the localized orbitals are not truncated. We are currently exploring the magnitude and nature of the energy drift caused by truncating the localized orbitals.

Abstract Author(s): Ian S. Dunn, Daniel Osei-Kuffuor, Jean-Luc Fattebert