What are the corrections to the energy in a quantum mechanical system?

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SUMMARY

The discussion centers on the corrections to eigenenergies in a quantum mechanical system influenced by a perturbation, represented as H = H0 + H'. The exact eigenenergies of the perturbed Hamiltonian are E = V_0(1-ε) and E = V_0(1-ε²), while the unperturbed eigenenergies are both E = V_0. The first-order corrections to the unperturbed eigenenergies are E = 0 and E = -εV0. The conclusion drawn is that since the unperturbed energies are identical, the specific assignment of corrections to these energies is inconsequential.

PREREQUISITES
  • Understanding of quantum mechanics principles, specifically Hamiltonians.
  • Familiarity with perturbation theory in quantum mechanics.
  • Knowledge of eigenenergies and eigenstates in quantum systems.
  • Access to "Griffiths Intro to QM" for reference to specific exercises.
NEXT STEPS
  • Study perturbation theory in quantum mechanics in detail.
  • Review the concept of eigenvalues and eigenstates in quantum systems.
  • Examine specific examples of first-order corrections in quantum mechanics.
  • Read exercise 6.9 in "Griffiths Intro to QM" for practical application.
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Students and educators in quantum mechanics, particularly those studying perturbation theory and eigenenergy corrections. This discussion is beneficial for anyone seeking to deepen their understanding of quantum systems and their mathematical formulations.

Niles
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Homework Statement


Hi all.

We are looking at a quantum mechanical system, where there is a perturbation H', so H = H0 + H', where H0 is the unperturbed Hamiltonian.

The exact eigenenergies (i.e. the eigenenergies of H) are given by:

[tex] E = V_0(1-\epsilon) \quad \tex{and}\quad E = V_0(1-\epsilon^2).[/tex]

So far so good. The eigenenergies of H0 (i.e. the unperturbed eigenenergies) are given by:

[tex] E = V_0 \quad \tex{and}\quad E = V_0.[/tex]

The first order corrections to the eigenenergies of H0 are given by: [itex]E=0[/itex] and [itex]E=-\epsilon V_0[/itex].

Here my question: How do I generally know which correction "belongs" to which unperturbed energy?

My book is "Griffiths Intro to QM", so feel free to quote from there: The above example is exercise 6.9.

Thanks in advance.Niles.
 
Last edited:
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Ok, I answered this question myself. The energies are the same, so it doesn't matter which energy we add the constants to.
 

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