M. Speis et al., Quantum mechanical calculations of molecular properties and ideal gas heatcapacity of difluoromethane, FLU PH EQUI, 170(2), 2000, pp. 285-296
Ideal gas heat capacities are important for the calculation of caloric prop
erties of real fluids. But as shown in the past, they are not always availa
ble with required accuracy or are still lacking. In this paper, we combine
quantum mechanical calculations and statistical thermodynamics. In order to
find a route to a reliable prediction of ideal gas heat capacity data, we
applied various quantum mechanical methods differing by computational effor
t to difluoromethane (CH2F2). Only the structural formula and fundamental p
hysical constants enter into the calculations. It is shown that quantum mec
hanics leads to accurate molecular data. Reliable experimental heat capacit
y data reveal that an accuracy of better than 0.5% is obtained for the idea
l gas heat capacity of difluoromethane. (C) 2000 Elsevier Science B.V. All
rights reserved.