Pair Interaction Models for σ_w

Abstract

In 1962, Raynes, Buckingham and Bernstein [15] published an entirely different theory for the calculation of medium shifts, which is basically a statistical mechanical model. All possible medium effects can be calculated in this theory, but in the derivation given below we will restrict ourselves to σ_w. Using a general virial theorem [40] one may write:

$$\sigma = {\sigma _0} + \frac{{{\sigma _1}}}{{{V_M}}} + \frac{{{\sigma _2}}}{{V_M^2}} + ... $$

((37))

where σ is the shielding in a medium, σ₀ the corresponding shielding of the solute in vacuo, V_M is the molar volume of the medium (tobe averaged on a mole fraction basis in case of mixtures), σ₁ is the 2^nd virial coefficient of corresponding to binary collisions while σ₂, σ₃... correspond to ternary and higher order collisions.