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arXiv · 1607.06404

Energy Continuity in Degenerate Density Functional Perturbation Theory

Mark C. Palenik·Brett I. Dunlap
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Abstract

Fractional occupation numbers can produce open-shell degeneracy in density functional theory. We develop the corresponding perturbation theory by requiring that a differentiable map connects the initial and perturbed states. The degenerate state connects to a single perturbed state which extremizes, but does not necessarily minimize or maximize, the energy with respect to occupation numbers. Using a system of three electrons in a harmonic oscillator potential, we relate the counterintuitive sign of first-order occupation numbers to eigenvalues of the electron-electron interaction Hessian.

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Mark C. Palenik, Brett I. Dunlap. 2016-07-21. Energy Continuity in Degenerate Density Functional Perturbation Theory. https://arxiv.org/abs/1607.06404

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