Theoretical concepts and calculation results of the spatial parity nonconserving (PNC) effects of
electron-electron and electron-nucleus nuclear spin-independent interactions in diatomic
homonuclear molecule H2 of parahydrogen are presented. The magnetic dipole transition between
the states with the same rotational number of the vibrational = ¬v 1 0 band in the H2 ground
electronic S+
g
1 state is considered. It is shown that in this situation these effects are of the same
order of magnitude. The H2 molecule is therefore the first example of molecular system where the
electron-electron PNC interaction can be directly observed. Since the constants of the electron-
nucleus PNC interaction have been already accurately measured in atomic experiments, the
electron-electron PNC interaction constant also can be extracted from the future experiments. In
other atoms and molecules the electron-electron PNC interaction is usually deeply screened by the
electron-nucleus one. Since the nuclei of H2 contain no neutrons, in such future experiments on the
PNC effect observation one can, in principle, measure the Weinberg angle (free parameter of the
standard model) with unprecedented accuracy.