EDM operator free from Schiff's theorem

We present a generalization of Schiff's transformation of electric dipole moments (EDM) in quantum field theory. Under the unitary transformation, the time and parity violating interaction ige/2ψ-barσμυγ5ψFμυ is transformed into a new form, but its nonrelativistic reduction has a unique form to which Schiff's theorem dose not apply. The relativistic corrections to the new EDM operator slightly increase the EDM, as given by b2(αZ)2 with b2≅2. It is thus seen that the calculation of the EDM with nonrelativistic Hartree-Fock wave functions presents a conservative but reliable estimation for the enhancement factor of the EDM in atoms. (author)