title: Petascale Orbital-Free Density Functional Theory Enabled by Small-Box Algorithms.
abstract: Orbital-free density functional theory (OFDFT) is a quantum-mechanics-based method that utilizes electron density as its sole variable. The main computational cost in OFDFT is the ubiquitous use of the fast Fourier transform (FFT), which is mainly adopted to evaluate the kinetic energy density functional (KEDF) and electron-electron Coulomb interaction terms. We design and implement a small-box FFT (SBFFT) algorithm to overcome the parallelization limitations of conventional FFT algorithms. We also propose real-space truncation of the nonlocal Wang-Teter KEDF kernel. The scalability of the SBFFT is demonstrated by efficiently simulating one full optimization step (electron density, energies, forces, and stresses) of 1,024,000 lithium (Li) atoms on up to 65,536 cores. We perform other tests using Li as a test material, including calculations of physical properties of different phases of bulk Li, geometry optimizations of nanocrystalline Li, and molecular dynamics simulations of liquid Li. All of the tests yield excellent agreement with the original OFDFT results, suggesting that the OFDFT-SBFFT algorithm opens the door to efficient first-principles simulations of materials containing millions of atoms.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Mohan
authors.initials: M
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences , P.O. Box 912, Beijing 100083, China.
authors.forename: Xiang-Wei
authors.initials: XW
authors.lastname: Jiang
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Houlong
authors.initials: H
authors.lastname: Zhuang
authors.affiliation: Material Science Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Lin-Wang
authors.initials: LW
authors.lastname: Wang
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University , Princeton, New Jersey 08544, United States.|Program in Applied and Computational Mathematics and the Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544, United States.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Carter