Polarization energy distribution for impurity molecules in dense gases

The polarization energy distribution of impurity molecules in dense gases is investigated. An approximate expression is derived for a random distribution and compared with results inferred from finite-temperature Monte Carlo studies for NO in argon (ρ⩽2.7×10²¹cm^-3). It is found that when ρ⩽1.8-2.0×10²¹cm^-3, the distribution has a similar shape with approximately the same peak position as that obtained from the Monte Carlo calculations. This result indicates that the peak position in this density range is due primarily to the r^-4 dependence of the polarization energy and the random positions of the host molecules and does not reflect the hard core of the intermolecular interactions.