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Eigenfunction Expansion: The Free Particle

Abstract
This document describes how, given an initial wave function, the wave function at time t can be found. First the initial wave function is decomposed into an expansion of the Hamiltonian eigenfunctions. Time dependence is then applied to these eigenfunctions. Finally, the wave function in x-space is recreated from the expansion.

A free particle gaussian wave packet is used as an example. All calculations are done discretely, such that they may readily be implemented in MATLAB®.

Documents are available below as PDF files.

  • Notation (PDF
  • Free Particle Time Dependence (PDF)
    • Computing the Fourier Transform (PDF)
    • Computing the time dependent amplitude function (PDF
    • Computing the Inverse Fourier Transform (PDF

  • Numerical Considerations (PDF
  • Generalizations: Adding an extra parameter (PDF

 

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