Abstract
Computations of the relative concentrations are reported for the two isomers of Lu3N@C-80 experimentally known, i.e., produced by encapsulation into the isolated-pentagon-rule (IPR) C-80 cages with I-h and symmetries. The calculations are mostly based on the density-functional theory (DFT) treatments with the B3LYP functional.
The inter-isomeric energetics is further refined with the MP2 perturbation method which places the endohedral higher in the potential energy by 16.9 kcal/mol. The isomeric populations are evaluated using the Gibbs energy in a broad temperature interval.
The computations performed with the floating-encapsulate-model (FEM) treatment can reasonably reproduce the observed isomeric ratio, thus pointing out a need for adequate representation of the dynamic endohedral symmetry.