Helium energy level diagram for ground and first excited states

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SUMMARY

The discussion focuses on constructing a qualitative energy level diagram for a helium atom where both electrons are replaced by spin-1 particles. The Hamiltonian is analyzed, particularly under perturbation theory, to illustrate energy levels when both particles occupy the n=1 state versus when one is in the n=1 state and the other in the (n,l,m)=(2,0,0) state. The wavefunctions are expressed in terms of hydrogenic single-particle wavefunctions and spin wavefunctions, revealing the necessary symmetry properties for bosons. The degeneracy of each level is also discussed, emphasizing the implications of spin multiplicities when combining two spin-1 particles.

PREREQUISITES
  • Quantum mechanics fundamentals, particularly Hamiltonians and perturbation theory.
  • Understanding of hydrogenic wavefunctions and their properties.
  • Knowledge of spin statistics, specifically the behavior of bosons and fermions.
  • Familiarity with angular momentum coupling and spin multiplicities.
NEXT STEPS
  • Study perturbation theory applications in quantum mechanics.
  • Explore the properties of hydrogenic wavefunctions in greater detail.
  • Learn about the addition of angular momentum and spin in quantum systems.
  • Investigate the implications of particle statistics on wavefunction symmetry.
USEFUL FOR

This discussion is beneficial for physicists, particularly those specializing in quantum mechanics, atomic physics, and particle statistics, as well as students seeking to deepen their understanding of energy level diagrams and wavefunction properties in multi-particle systems.

MeiLai
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Consider a helium atom where both electrons are replaced by identical charged particles of spin-1. Ignoring the motion of the nucleus, the Hamiltonian is [see attachment 1]

Construct an energy level diagram ( qualitatively ) for this "atom", when both particles are in the n=1 state, and when one particle is in the n=1 state and the other is in the state (nlm)=(200). Do this by treating the term in the Hamiltonian as a perturbation. Write out the space and spin wavefunctions for each level in terms of the single particle hydrogenic wavefunctions [phi]nlm spin wavefunctions [chi]s,m-sub-s. Show the splitting qualitatively, and state the degeneracy of each level.
 

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The electrons have been replaced by particles of spin 1. Are these particles bosons or fermions? Should their wavefunctions be symmetric or antisymmetric under particle interchange? Also, you need to reconsider what kind of spin multiplicities you get when you add two spin 1 particles.
 
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