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Spectral quadrature for the first principles study of crystal defects: Application to magnesium

Ghosh, Swarnava and Bhattacharya, Kaushik (2020) Spectral quadrature for the first principles study of crystal defects: Application to magnesium. . (Unpublished)

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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.

Item Type:Report or Paper (Discussion Paper)
Related URLs:
URLURL TypeDescription Paper
Ghosh, Swarnava0000-0003-3800-5264
Bhattacharya, Kaushik0000-0003-2908-5469
Additional Information:This research was performed when S.G. held a position at the California Institute of Technology. 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 Caltech High Performance Cluster partially supported by a grant from the Gordon and Betty Moore Foundation, and the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562.
Funding AgencyGrant Number
Army Research LaboratoryW911NF-12-2-0022
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:Spectral quadrature, Linear-Scaling, Density Functional Theory, Defects, Magnesium
Record Number:CaltechAUTHORS:20210729-195436164
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:110073
Deposited By: Tony Diaz
Deposited On:02 Aug 2021 18:43
Last Modified:02 Aug 2021 18:43

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