Fisher Information-Based Optimization of Mapped Fourier Grid Methods

The mapped Fourier grid method (mapped-FGM) is a simple and efficient discrete variable representation (DVR) numerical technique for solving atomic radial Schrödinger differential equations. It is set up on equidistant grid points, and the mapping, a suitable coordinate transformation to the radial...

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Main Authors: Sotiris Danakas, Samuel Cohen
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Atoms
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Online Access:https://www.mdpi.com/2218-2004/12/10/50
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author Sotiris Danakas
Samuel Cohen
author_facet Sotiris Danakas
Samuel Cohen
author_sort Sotiris Danakas
collection DOAJ
description The mapped Fourier grid method (mapped-FGM) is a simple and efficient discrete variable representation (DVR) numerical technique for solving atomic radial Schrödinger differential equations. It is set up on equidistant grid points, and the mapping, a suitable coordinate transformation to the radial variable, deals with the potential energy peculiarities that are incompatible with constant step grids. For a given constrained number of grid points, classical phase space and semiclassical arguments help in selecting the mapping function and the maximum radial extension, while the energy does not generally exhibit a variational extremization trend. In this work, optimal computational parameters and mapping quality are alternatively assessed using the extremization of (coordinate and momentum) Fisher information. A benchmark system (hydrogen atom) is employed, where energy eigenvalues and Fisher information are traced in a standard convergence procedure. High-precision energy eigenvalues exhibit a correlation with the extrema of Fisher information measures. Highly efficient mapping schemes (sometimes classically counterintuitive) also stand out with these measures. Same trends are evidenced in the solution of Dalgarno–Lewis equations, i.e., inhomogeneous counterparts of the radial Schrödinger equation occurring in perturbation theory. A detailed analysis of the results, implications on more complex single valence electron Hamiltonians, and future extensions are also included.
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spelling doaj-art-958df274eddf4e33a2723b675f88a4ee2025-08-20T02:10:57ZengMDPI AGAtoms2218-20042024-10-0112105010.3390/atoms12100050Fisher Information-Based Optimization of Mapped Fourier Grid MethodsSotiris Danakas0Samuel Cohen1Atomic and Molecular Physics Laboratory, Physics Department, University of Ioannina, 45110 Ioannina, GreeceAtomic and Molecular Physics Laboratory, Physics Department, University of Ioannina, 45110 Ioannina, GreeceThe mapped Fourier grid method (mapped-FGM) is a simple and efficient discrete variable representation (DVR) numerical technique for solving atomic radial Schrödinger differential equations. It is set up on equidistant grid points, and the mapping, a suitable coordinate transformation to the radial variable, deals with the potential energy peculiarities that are incompatible with constant step grids. For a given constrained number of grid points, classical phase space and semiclassical arguments help in selecting the mapping function and the maximum radial extension, while the energy does not generally exhibit a variational extremization trend. In this work, optimal computational parameters and mapping quality are alternatively assessed using the extremization of (coordinate and momentum) Fisher information. A benchmark system (hydrogen atom) is employed, where energy eigenvalues and Fisher information are traced in a standard convergence procedure. High-precision energy eigenvalues exhibit a correlation with the extrema of Fisher information measures. Highly efficient mapping schemes (sometimes classically counterintuitive) also stand out with these measures. Same trends are evidenced in the solution of Dalgarno–Lewis equations, i.e., inhomogeneous counterparts of the radial Schrödinger equation occurring in perturbation theory. A detailed analysis of the results, implications on more complex single valence electron Hamiltonians, and future extensions are also included.https://www.mdpi.com/2218-2004/12/10/50DVRmapped Fourier grid methodSchrödinger equation solutionFisher information measureconvergence evaluation
spellingShingle Sotiris Danakas
Samuel Cohen
Fisher Information-Based Optimization of Mapped Fourier Grid Methods
Atoms
DVR
mapped Fourier grid method
Schrödinger equation solution
Fisher information measure
convergence evaluation
title Fisher Information-Based Optimization of Mapped Fourier Grid Methods
title_full Fisher Information-Based Optimization of Mapped Fourier Grid Methods
title_fullStr Fisher Information-Based Optimization of Mapped Fourier Grid Methods
title_full_unstemmed Fisher Information-Based Optimization of Mapped Fourier Grid Methods
title_short Fisher Information-Based Optimization of Mapped Fourier Grid Methods
title_sort fisher information based optimization of mapped fourier grid methods
topic DVR
mapped Fourier grid method
Schrödinger equation solution
Fisher information measure
convergence evaluation
url https://www.mdpi.com/2218-2004/12/10/50
work_keys_str_mv AT sotirisdanakas fisherinformationbasedoptimizationofmappedfouriergridmethods
AT samuelcohen fisherinformationbasedoptimizationofmappedfouriergridmethods