This paper is devoted to the calculation of parity nonconserving (PNC) effects in the diatomic
homonuclear molecule of oxygen O 2 . For this purpose the magnetic dipole transition
S ¬ S+ -
b Xg g
1 3 was considered. It was believed that the weak electron–electron interaction
prevails over the weak interaction of electrons with nuclei in this case. This idea appeared not to
be justified for molecular oxygen. As it turns out from our calculations, the parity
nonconservation degree for the weak electron–nucleus interaction is of the order
 = -·1.4 10eN 11 and for the weak electron–electron interaction is by two orders smaller
 = -·1.1 10ee 13. Nevertheless, a PNC experiment for the observation of the weak electron–
nucleus interaction looks sufficiently feasible (previously, such experiments were carried out
only with atoms).