Chen Mohan, Jiang Xiang-Wei, Zhuang Houlong, Wang Lin-Wang, Carter Emily A
Department of Mechanical and Aerospace Engineering, Princeton University , Princeton, New Jersey 08544, United States.
State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences , P.O. Box 912, Beijing 100083, China.
J Chem Theory Comput. 2016 Jun 14;12(6):2950-63. doi: 10.1021/acs.jctc.6b00326. Epub 2016 May 16.
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.
无轨道密度泛函理论（OFDFT）是一种基于量子力学的方法，它将电子密度作为唯一变量。OFDFT中的主要计算成本是普遍使用快速傅里叶变换（FFT），其主要用于评估动能密度泛函（KEDF）和电子-电子库仑相互作用项。我们设计并实现了一种小盒FFT（SBFFT）算法，以克服传统FFT算法的并行化限制。我们还提出了对非局部Wang-Teter KEDF核进行实空间截断。通过在多达65536个核心上高效模拟1024000个锂（Li）原子的一个完整优化步骤（电子密度、能量、力和应力），证明了SBFFT的可扩展性。我们以锂作为测试材料进行了其他测试，包括计算块状锂不同相的物理性质、纳米晶锂的几何优化以及液态锂的分子动力学模拟。所有测试结果与原始OFDFT结果都非常吻合，这表明OFDFT-SBFFT算法为包含数百万原子的材料的高效第一性原理模拟打开了大门。
