perturbation theory without multipole expansion

[sanfvers]

If the interaction term of the nucleus and electron cloud would not be multipole expanded, the distinction into a hierarchy of energy scales would not be convenient. As a part of the multipole expansion (the zero order terms) of the interaction term is part of the ‘known’ Hamiltonian, it would be difficult to apply perturbation theory if the interaction term would not have been expanded.

[Author]

Posts