Effects of external electric field and internuclear length on effective electric field for measurement of electron electric dipole moment

This paper studies factors which may affect the effective electric field of observation experiments of the electron electric dipole moment. Particularly, the external electric field used in experiments and the internuclear length between two atoms in polar molecules are paid attention to. YbF and ThO are chosen for polar molecules used in observational experiments of the electron electric dipole moment. For the study of the effect of the external electric field, we confirm that this external electric field is negligible in computations of the effective electric field, since this external electric field is much smaller than the internal electric field in the molecules. The effect of the internuclear length is investigated in a viewpoint of the relation with the molecular electric dipole moment.