  Advantages of using a low-energy effective theory to study bound state
properties are briefly discussed, and a nonperturbative implementation of such
an effective theory is described within the context of nonrelativistic quantum
mechanics. The hydrogen atom, in the approximation of a structureless,
infinite-mass nucleus, but with the leading relativistic and radiative
corrections included, is used to demonstrate the construction and solution of
the effective theory. The resulting Hamiltonian incorporates a finite
ultraviolet cutoff and can be solved nonperturbatively. An appendix lists
explicit formulae for the various matrix elements necessary to diagonalize the
Hamiltonian using gaussian basis sets.
