Post-processing of the planewave approximation of Schrödinger equations. Part I: linear operators

Abstract : In this article, we prove a priori error estimates for the perturbation-based post-processing of the plane-wave approximation of Schrödinger equations introduced and tested numerically in previous works [6, 7]. We consider here a Schrödinger operator $H = − 1/2 ∆ + V$ on $L^2 (Ω$), where $Ω$ is a cubic box with periodic boundary conditions, and where V is a multiplicative operator by a regular-enough function V. The quantities of interest are, on the one hand, the ground-state energy defined as the sum of the lowest N eigenvalues of H , and, on the other hand, the ground-state density matrix, that is the spectral projector on the vector space spanned by the associated eigenvectors. Such a problem is central in first-principle molecular simulation, since it corresponds to the so-called linear subproblem in Kohn-Sham density functional theory (DFT). Interpreting the exact eigenpairs of H as perturbations of the numerical eigenpairs obtained by a variational approximation in a plane-wave (i.e. Fourier) basis, we compute first-order corrections for the eigenfunctions, which are turned into corrections on the ground-state density matrix. This allows us to increase the accuracy of both the ground-state energy and the ground-state density matrix at a low computational extra-cost. Indeed, the computation of the corrections only requires the computation of the residual of the solution in a larger plane-wave basis and two Fast Fourier Transforms per eigenvalue.
Type de document :
Pré-publication, Document de travail
2018
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https://hal.archives-ouvertes.fr/hal-01908039
Contributeur : Geneviève Dusson <>
Soumis le : mardi 20 novembre 2018 - 23:58:23
Dernière modification le : vendredi 4 janvier 2019 - 17:33:39

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Post_processing_part1.pdf
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  • HAL Id : hal-01908039, version 2

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Eric Cancès, Geneviève Dusson, Yvon Maday, Benjamin Stamm, Martin Vohralík. Post-processing of the planewave approximation of Schrödinger equations. Part I: linear operators. 2018. 〈hal-01908039v2〉

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