CALCULATIONS OF MAGNETIC-PROPERTIES .5. ELECTRON-CORRELATED HYPERMAGNETIZABILITIES (COTTON-MOUTON EFFECT) FOR H-2, N-2, HF, AND CO

Calculations of the hypermagnetizabilities (eta) at the self-consisten t-field (SCF) and second-order Moller-Plesset perturbation theory (MP2 ) levels of theory are reported for H-2, N-2, HF, and CO. Electron cor relation is found to be unimportant for H-2, but very important for th e other three molecules. The individual components of eta are more aff ected by correlation effects than the hypermagnetizability anisotropy (Delta eta) which mediates the birefringence of a material in the pres ence of a magnetic field (the Cotton-Mouton effect). The zero-point-vi brational averaging, pure vibrational corrections, and frequency depen dence are important for the individual components, but are less import ant for Delta eta due to cancellation between the various contribution s. Excellent agreement is found with the previous theoretical results for H-2, but only fair agreement with the experimental results for N-2 and CO.