PhD Defense by Swarnava Ghosh

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 School of Civil and Environmental Engineering Ph.D. Thesis Defense AnnouncementEfficient Large-Scale Real-Space Electronic Structure Calculations BySwarnava Ghosh Advisor:Dr. Phanish Suryanarayana (CEE) Committee Members:Dr. Glaucio H. Paulino (CEE), Dr. Arash Yavari (CEE),Dr. Ting Zhu (ME), Dr. John E. Pask (Lawrence Livermore National Laboratory) Date & Time: Thursday, July 7, 2016, at 10:30AM Location: Sustainable Education Building, 122Calculations involving the electronic structure of matter provides valuable insight in understanding and predicting a wide range of materialsproperties. Over the course of the last few decades, Density Functional Theory (DFT) has been a reliable and popular ab-initio method. Theplane-wave basis is commonly employed for solving the DFT problem. However, the need for periodicity limits the effectiveness of theplane-wave basis in studying localized or partially periodic systems. Furthermore, efficient use utilization modern large-scale computerarchitectures is particularly challenging due to the non-locality of the basis. Real-space methods for solving the DFT problem provide anattractive alternative.In this work we present an accurate and efficient real-space formulation and parallel implementation of Density Functional Theory (DFT) forperforming ab-initio simulations of isolated clusters (molecules and nanostructures), periodic (infinite crystals) and partially periodic systems(slabs and nanowires). Using the finite-difference representation, local reformulation of the electrostatics, the Chebyshev polynomial filteredself-consistent field iteration, and a reformulation of the non-local component of the force, we develop SPARC (Simulation Package forAb-initio Real-space Calculations), a framework that enables the efficient evaluation of energies and atomic forces to within chemicalaccuracies in DFT. Through selected examples consisting of a variety of elements, we demonstrate that the developed framework obtainsexponential convergence in energy and forces with domain size; systematic convergence in the energy and forces with mesh-size to referenceplane-wave result at comparably high rates; forces that are consistent with the energy, both free from any noticeable `egg-box' effect; andaccurate ground-state properties including equilibrium geometries and vibrational spectra. We also demonstrate the weak and strong scalingbehavior of SPARC and compare with well-established and optimized plane-wave and other real-space implementations of DFT for systemsconsisting up to thousands of electrons. Overall, the developed framework is able to accurately and efficiently simulate the electronicstructure of a wide range of material systems and represents an attractive alternative to existing codes for practical DFT simulations.


  • Workflow Status: Published
  • Created By: Tatianna Richardson
  • Created: 06/22/2016
  • Modified By: Fletcher Moore
  • Modified: 10/07/2016


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