Representation of the Dirac equation and the variational principle



The performance of the variational method applied to the Dirac equation depends on the selected representation of this equation in four-dimensional spinor space. This dependence is analyzed. It is pointed out that the representations of Weyl and of Biedenharn have several attractive features. The usefulness of the so-called kinetically balanced Dirac equation is also briefly discussed. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006