Long-range spherical potential energy function from the second virial coefficient using decomposition into subspaces

The long-range dispersion part of a spherical potential energy function was recovered from simulated second virial data for the Ar-Ar system in the te mperature range 90 less than or equal to T/K less than or equal to 120. Usi ng the singular value decomposition method the potential was obtained for s everal dimensions of the four basic subspaces. In particular for the data g enerated and for dimension of the nullspace equal to two the potential was recovered almost exactly. For a larger basis set, n=128, where the simulate d data would be in error by 3.5% when compared with the experimental data, the potential could be recovered, using the stationary points, within an er ror of 0.3-2.0%. The present procedure also indicates a general strategy, w hen handling second virial experimental data in the low temperature region, to obtain the long-range part of the spherical potential function.