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Electronic Structure - quantum mechanics of solids

Density-functional theory (DFT) is widely used to describe the electronic structure of crystalline solids. I've worked with Jeff Nelson and others at Sandia to parallelize Car-Parinello DFT codes that represent electron wave functions with plane-wave basis sets. These codes are best suited to modeling materials with smoothly-varying valence states such as semiconductors and metals. Core electron states are represented with compute-efficient pseudo- potentials.

Plane-wave DFT codes require parallel FFTs to swap between real-space and reciprocal-space representations of various operators. Our work on parallel FFTs is described here. Other parallel issues addressed in the codes include Gram-Schmidt orthonormalization of a large set of wave functions and load- balancing issues that arise from working on 2 different data sets -- one for the full 3-d FFT mesh and one for the spherical subset of mesh points that correspond to wave vectors whose length is within a cutoff distance. We devised a novel way of mapping back and forth between these 2 data sets to maintain load-balance in each stage of the computation; it's described in the 1993 PRB paper below.

Collaborators on this project:

These papers describe various aspects of the DFT work. The book chapter is the most recent and includes some discussion of our FFT methodology. The 1995 PRB article is an application of the code to amorphous carbon (other calcuations can be found by a literature search for J. S. Nelson or A. F. Wright articles). The earlier 1993 PRB article was our first explanation of our parallel strategy for plane-wave DFT codes.

Plane-wave Psuedopotential Electronic Structure Calculations on Parallel Supercomputers, J. S. Nelson and S. J. Plimpton, chapter in Topics in Computational Materials Science, edited by C. Y. Fong, published by World Scientific, 61-95 (1998). (abstract)

Basis-Set Convergence of Highly Defected Sites in Amorphous-Carbon, J. S. Nelson, E. B. Stechel, A. F. Wright, S. J. Plimpton, P. A. Schultz, M. P. Sears, Phys Rev B, 52, 9354-59 (1995). (abstract)

Plane-wave Electronic- Structure Calculations on a Parallel Supercomputer, J. S. Nelson, S. J. Plimpton, M. P. Sears, Phys Rev B, 47, 1765-1774 (1993). (abstract)