  Highly accurate closed-form approximations are given for the ground state and
first excited state wavefunctions and energies for a nonrelativistic particle
in a one-dimensional double square well potential with a square barrier in
between (so that the potential is a sequence of five constant pieces that
alternate in value from being above and below the ground state and first
excited state energies), under the assumption that the barrier is sufficiently
wide that the tunneling across it is very small.
