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Homework Help: Time-Independent Perturbation Theory

  1. May 17, 2016 #1
    1. The problem statement, all variables and given/known data
    I am working on a physics project for which I need to use perturbation theory to calculate the first- and second-order corrections to the eigenvalues and eigenvectors of a perturbed matrix. The unperturbed matrix is real and symmetric, and the eigenvalues and eigenvectors are easy to calculate. However, the perturbed matrix is complex and non-Hermitian (the perturbation introduces complex components on the main diagonal). I am new to perturbation theory. My question is whether I can use the standard matrix perturbation theory for Hermitian Hamiltonians, as explained in Chapter 6 of "Introduction to Quantum Mechanics" by Griffiths. Clearly, the unperturbed matrix needs to be Hermitian, but it doesn't seem as if the perturbed one has to be. I would just like to double-check this.

    2. Relevant equations

    3. The attempt at a solution
    I went through the derivation in Griffiths, and didn't see the assumption that the perturbed matrix has to be Hermitian being used anywhere.
  2. jcsd
  3. May 18, 2016 #2


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    Staff: Mentor

    I've never used perturbation theory with non-Hermitian matrices, but I don't foresee any problem in using the standard approach.
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