Zeitschrift für Physik D Atoms, Molecules and Clusters

, Volume 11, Issue 1, pp 15-28

First online:

Perturbation theory of relativistic corrections

1. The non-relativistic limit of the Dirac equation and a direct perturbation expansion
  • W. KutzelniggAffiliated withLehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


After a discussion of the problems associated with the non-relativistic limit of the Dirac equation and of the expansion of the exact eigenvalues and eigenfunctions of the H atom in powers ofc −2 the traditional approaches for a perturbation theory of relativistic effects are critically reviewed. Then a direct perturbation theory is presented, that is characterized by a change of the metric in 4-component spinor space such that the Lévy-Leblond equation appears as the straightforward non-relativistic limit of the Dirac equation. The various orders in perturbation theory of the energy and the wave function are derived first in a direct way, then in a resolvent formalism. The formulas are very compact and easily generalizeable to arbitrary order. All integrals that arise to any order exist, and no controlled cancellation of divergent terms (as in other approaches) is necessary. In the same philosophy an iterative approach towards the solution of the Dirac equation is derived, in which the solution of the Schrödinger equation is the first iteration step.


11..10.Qr 31.15.+q 31.30.Jv