Forming Hydrogen wave functions with real spherical harmonics

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Discussion Overview

The discussion centers on the application of real spherical harmonics in constructing hydrogen wave functions for a computational project. Participants explore the implications of using real spherical harmonics for the angular part of the wave function and its relation to the standard spherical harmonics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about applying real spherical harmonics to build a strictly real hydrogen wave function and seeks references.
  • Another participant explains how to construct the angular part of the p orbitals using transformations from the standard spherical harmonics to real spherical harmonics.
  • A question is posed regarding whether the wave function using real spherical harmonics satisfies the same Schrödinger equation as the one using complex spherical harmonics.
  • A later reply suggests acting on the new functions with the Hamiltonian to check the behavior with respect to the magnetic quantum number m.
  • Another participant confirms that states with different m are degenerate in the hydrogen atom, indicating that linear combinations of these states, including real ones, remain eigenstates.
  • It is noted that while real spherical harmonics are eigenfunctions of the hydrogen atom's Hamiltonian, they do not serve as simultaneous eigenfunctions of the angular momentum operator ##\hat{l}_z##, unlike the complex spherical harmonics.

Areas of Agreement / Disagreement

Participants express differing views on the implications of using real spherical harmonics, particularly regarding their eigenfunction properties and their relationship to the Schrödinger equation. The discussion remains unresolved on some aspects, particularly the practical application and implications of these transformations.

Contextual Notes

There are limitations regarding the assumptions made about the properties of real spherical harmonics and their relationship to the Hamiltonian and angular momentum operators, which are not fully explored in the discussion.

dipole
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Hi, I'm a little confused about how to apply the real spherical harmonics when building a hydrogen wave function.

I'm doing a computational project, so I want to work with a wave function which is strictly real, and I'm hoping I can do so by building the orbitals using the real spherical harmonics, [itex]p_x, p_y, p_z,...[/itex] etc. Can someone give me a link or reference as to how that works?

Thanks.
 
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dipole said:
I'm doing a computational project, so I want to work with a wave function which is strictly real, and I'm hoping I can do so by building the orbitals using the real spherical harmonics, [itex]p_x, p_y, p_z,...[/itex] etc. Can someone give me a link or reference as to how that works?
Not sure exactly what you want, but you construct the angular part of the p orbitals by transforming from the usual basis of spherical harmonics ##Y_{1,1}##, ##Y_{1,0}##, ##Y_{1,-1}## to
$$
p_x = \frac{1}{\sqrt{2}} \left( Y_{1,-1} - Y_{1,1} \right) \\
p_y = \frac{i}{\sqrt{2}} \left( Y_{1,-1} + Y_{1,1} \right) \\
p_z = Y_{1,0}
$$
 
Hi, so my question is, does the wave function,

[tex]\psi_{nlm}(\vec{x}) = R_{n\ell}(r)p_{i}(\theta,\phi)[/tex]

where [itex]p_{i}(\theta,\phi)[/itex] are the real spherical harmonics, satisfy the same Schrödinger equation as the wave function

[tex]\psi_{nlm}(\vec{x}) = R_{n\ell}(r)Y_{\ell}^m(\theta,\phi)[/tex] ?

Thanks.
 
Just act with H, especially with the part containing the phi-derivative, on the new functions and check what happens with m
 
dipole said:
Hi, so my question is, does the wave function,

[tex]\psi_{nlm}(\vec{x}) = R_{n\ell}(r)p_{i}(\theta,\phi)[/tex]

where [itex]p_{i}(\theta,\phi)[/itex] are the real spherical harmonics, satisfy the same Schrödinger equation as the wave function

[tex]\psi_{nlm}(\vec{x}) = R_{n\ell}(r)Y_{\ell}^m(\theta,\phi)[/tex] ?

Thanks.

Yes, the states with different m are degenerate in the hydrogen atom. Hence any linear combination (notably the real ones) of these states is again an eigenstate.
 
To add to what Tom and DrDu wrote, just note that while the real spherical harmonics are eigenfunctions of the Hamiltonian of the hydrogen atom, they are not simultaneously eigenfunctions of ##\hat{l}_z##, as the complex ##Y_{l,m}## are.
 

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