Augmented Lagrangian formulation of Orbital-Free Density Functional Theory

Abstract

We present an Augmented Lagrangian formulation and its real-space implementation for non-periodic orbital-free Density Functional Theory (OF-DFT) calculations. In particular, we rewrite the constrained minimization problem of OF-DFT as a sequence of minimization problems without any constraint, thereby making it amenable to powerful unconstrained optimization algorithms. Further, we develop a parallel implementation of this approach for the Thomas-Fermi-von Weizscaker (TFW) kinetic energy functional in the framework of higher-order finite-differences and the conjugate gradient method. With this implementation, we establish that the Augmented Lagrangian approach is highly competitive compared to the penalty and Lagrange multiplier methods. Additionally, we show that higher-order finite-differences represent a computationally efficient discretization for performing OF-DFT simulations. Overall, we demonstrate that the proposed formulation and implementation is both efficient and robust by studying selected examples, including systems consisting of thousands of atoms. We validate the accuracy of the computed energies and forces by comparing them with those obtained by existing plane-wave methods.

arXiv comment21 pages, 4 figures and 10 tables. Typos corrected

References in corpus (6)

• O(N) methods in electronic structure calculations
• Coarse-graining Kohn-Sham Density Functional Theory
• Conjugate-Gradient Optimization Method for Orbital-free Density Functional Calculations
• Kinetic energy density functionals for non-periodic systems
• Higher-order adaptive finite-element methods for orbital-free density functional theory
• Nonlinear instability of density-independent orbital-free kinetic energy functionals

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