Distributed Phase Acquisition in a Wave Function

A separable $x-y$ model is solved for a specialized vector potential (no magnetic and weak electric fields) penetrating slowly$\mathbf{\text{,}}$ adiabatically into and across a rectangular box to which an electron is confined. The time-dependent Schr"odinger equation has adiabatic solutions, in which gradual phase acquisitions occur for {\it parts} of the electronic wave function. For a closed trajectory of the source, the initial and after-return wave functions are shown to be simultaneously co-degenerate solutions of the Hamiltonian, which situation repeats itself for further cyclic motion of the source.