Ideal-gas properties of new refrigerants from quantum mechanical ab initio calculations

Theoretical predictions of ideal-gas properties from molecular data such as structure, vibrational frequencies, and the barrier of internal rotation are compared to recent experimental data on heat capacities of new refrigerants. It is demonstrated that the required molecular data can be obtained from quantum-mechanical ab initio calculations with sufficient accuracy to provide heat capacities with an accuracy of ±2%. Further improvement of the approach appears feasible. This is of great practical significance, since molecular data obtained from experimental spectra tend to be inaccurate for systems of technical interest with somewhat larger molecules, like the new refrigerants.