Abstract
We calculate an effective electric field on the unpaired electron in the YbF molecule. This field determines the sensitivity of the molecular experiment to the electric dipole moment of the electron. We use experimental values of the spin-doubling constant to estimate the admixture of the configuration with the hole in the 4f shell of ytterbium to the ground state of the molecule. This admixture reduces the field by 7%. Our value for the effective field is .