Forming Hydrogen wave functions with real spherical harmonics

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SUMMARY

This discussion focuses on constructing hydrogen wave functions using real spherical harmonics for computational projects. The transformation from complex spherical harmonics to real spherical harmonics is essential for building strictly real wave functions, specifically for p orbitals defined as p_x, p_y, and p_z. The wave function expressed as ψ_{nlm}(\vec{x}) = R_{nℓ}(r)p_{i}(\theta,\phi) satisfies the same Schrödinger equation as the complex version ψ_{nlm}(\vec{x}) = R_{nℓ}(r)Y_{ℓ}^m(\theta,\phi), highlighting the degeneracy of states with different m values in the hydrogen atom.

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  • Understanding of quantum mechanics and the Schrödinger equation
  • Familiarity with spherical harmonics and their properties
  • Knowledge of hydrogen atom wave functions and quantum numbers
  • Basic computational skills for implementing wave functions in programming
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  • Research the mathematical transformation from complex spherical harmonics to real spherical harmonics
  • Learn about the properties of eigenfunctions in quantum mechanics, particularly for the hydrogen atom
  • Explore computational methods for simulating quantum systems using real spherical harmonics
  • Study the implications of degeneracy in quantum states and its applications in quantum mechanics
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Researchers, computational physicists, and students working on quantum mechanics projects, particularly those focused on hydrogen atom wave functions and real spherical harmonics.

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, p_x, p_y, p_z,... 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, p_x, p_y, p_z,... 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,

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

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

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

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,

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

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

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

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.
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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