Investigation of a Grid-Free Density Functional Theory (DFT) Approach
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Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).
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The Department of Chemistry was founded in 1880.
Dates of Existence
1880-present
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- College of Liberal Arts and Sciences (parent college)
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Abstract
Density functional theory(DFT) has gained popularity, because it can frequently give accurate energies and geometries. Because evaluating DFT integrals fully analytically is usually impossible, most implementations use numerical quadrature over grid points, which can lead to numerical instabilities. To avoid these instabilities, the Almlöf-Zheng (AZ) grid-free approach was developed. This approach involves application of the resolution of the identity (RI) to evaluate the integrals. The focus of the current work is on the implementation of the AZ approach into the electronic structure code GAMESS, and on the convergence of the resolution of the identity with respect to basis set in the grid-free approach. Both single point energies and gradients are calculated for a variety of functionals and molecules. Conventional atomic basis sets are found to be inadequate for fitting the RI, particularly for gradient corrected functionals. Further work on developing auxiliary basis set approaches is warranted.
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The following article appeared in Journal of Chemical Physics 109 (1998): 9959, and may be found at doi:10.1063/1.476494.