The time-independent mean-field method for the calculation of matrix elements of nonrelativistic propagators is based on a variational principle whose nonlinearity induces a multiplicity of variational solutions. Several of them can break any symmetry shared by the Hamiltonian and initial and final states. We describe a soluble model where, in particular, time reversal and parity breakings occur. Such breakings account for important properties of propagation amplitudes. © 1996 The American Physical Society.

• Received 27 December 1994

DOI:https://doi.org/10.1103/PhysRevA.53.611