Calculations of magnetic properties. V. Electron‐correlated hypermagnetizabilities (Cotton–Mouton effect) for H₂, N₂, HF, and CO Available to Purchase

Calculations of the hypermagnetizabilities (η) at the self‐consistent‐field (SCF) and second‐order Mo/ller–Plesset perturbation theory (MP2) levels of theory are reported for H₂, N₂, HF, and CO. Electron correlation is found to be unimportant for H₂, but very important for the other three molecules. The individual components of η are more affected by correlation effects than the hypermagnetizability anisotropy (Δη) which mediates the birefringence of a material in the presence of a magnetic field (the Cotton–Mouton effect). The zero‐point‐vibrational averaging, pure vibrational corrections, and frequency dependence are important for the individual components, but are less important for Δη due to cancellation between the various contributions. Excellent agreement is found with the previous theoretical results for H₂, but only fair agreement with the experimental results for N₂ and CO.