Abstract
We present an accurate and efficient finite-difference formulation and parallel implementation of Kohn-Sham Density (Operator) Functional Theory (DFT) for non periodic systems embedded in a bulk environment. Specifically, employing non-local pseudopotentials, local reformulation of electrostatics, and truncation of the spatial Kohn-Sham Hamiltonian, and the Linear Scaling Spectral Quadrature method to solve for the pointwise electronic fields in real-space and the non-local component of the atomic force, we develop a parallel finite difference framework suitable for distributed memory computing architectures to simulate non-periodic systems embedded in a bulk environment. Choosing examples from magnesium-aluminum alloys, we first demonstrate the convergence of energies and forces with respect to spectral quadrature polynomial order, and the width of the spatially truncated Hamiltonian. Next, we demonstrate the parallel scaling of our framework, and show that the computation time and memory scale linearly with respect to the number of atoms. Next, we use the developed framework to simulate isolated point defects and their interactions in magnesium-aluminum alloys. Our findings conclude that the binding energies of divacancies, Al solute-vacancy and two Al solute atoms are anisotropic and are dependent on cell size. Furthermore, the binding is favorable in all three cases.
| Original language | English |
|---|---|
| Article number | 111035 |
| Journal | Journal of Computational Physics |
| Volume | 456 |
| DOIs | |
| State | Published - May 1 2022 |
Funding
This research was performed when S.G. held a position at the California Institute of Technology. We thank the anonymous reviewers for their valuable comments and suggestions. The work was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-12-2-0022 . The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. The computations presented here were conducted on the Resnick High-Performance Center, a facility supported by Resnick Sustainability Institute at the California Institute of Technology, and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562 . Part of this research used resources of the Oak Ridge Leadership Computing Facility, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory under contract DE-AC05-00OR22725 . This research was performed when S.G. held a position at the California Institute of Technology. We thank the anonymous reviewers for their valuable comments and suggestions. The work was sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911NF-12-2-0022. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. The computations presented here were conducted on the Resnick High-Performance Center, a facility supported by Resnick Sustainability Institute at the California Institute of Technology, and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562. Part of this research used resources of the Oak Ridge Leadership Computing Facility, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory under contract DE-AC05-00OR22725.
| Funders | Funder number |
|---|---|
| National Science Foundation | ACI-1548562 |
| Office of Science | |
| Oak Ridge National Laboratory | DE-AC05-00OR22725 |
| Army Research Laboratory | W911NF-12-2-0022 |
| California Institute of Technology | |
| Resnick Sustainability Institute for Science, Energy and Sustainability, California Institute of Technology |
Keywords
- Defects
- Density functional theory
- Linear-scaling
- Magnesium
- Spectral quadrature