Diamagnetic susceptibility of methane

Theoretical calculations of the diamagnetic susceptibility of methane CH 4 have been made on the basis of the molecular-orbital and electron-pair approximate wave functions. The results are compared with the self-consistent-field value, and it is shown that in this latter an error of about 25% is due to the preliminary averaging of the positive charges on the four protons. The new values agree well among themselves, but are still considerably larger than the experimental value. The reasons for this are briefly discussed.