  The a(1) state of PbO can be used to measure the electric dipole moment of
the electron d_e. We discuss a semiempirical model for this state, which yields
an estimate of the effective electric field on the valence electrons in PbO.
Our final result is an upper limit on the measurable energy shift, which is
significantly larger than was anticipated earlier: $ 2|W_d|d_e \ge 2.4\times
10^{25} \textrm{Hz} [ \frac{d_e}{e \textrm{cm}} ]$.
