IDEAL-GAS PROPERTIES OF NEW REFRIGERANTS FROM QUANTUM-MECHANICAL AB-INITIO CALCULATIONS

Theoretical predictions of ideal-gas properties from molecular data su ch as structure, vibrational frequencies, and the barrier of internal rotation are compared to recent experimental data on heat capacities o f new refrigerants. It is demonstrated that the required molecular dat a 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 exper imental spectra tend to be inaccurate for systems of technical interes t with somewhat larger molecules, like the new refrigerants.