The Antoine equation is a class of semi-empirical correlations describing the relation between vapor pressure and temperature for pure substances.
(760 mmHg = 101.325 kPa = 1.000 atm = normal pressure) This example shows a severe problem caused by using two different sets of coefficients.
This causes severe problems for computational techniques which rely on a continuous vapor pressure curve.
Two solutions are possible: The first approach uses a single Antoine parameter set over a larger temperature range and accepts the increased deviation between calculated and real vapor pressures.
The example calculation with the converted parameters (for K and Pa): becomes (The small differences in the results are only caused by the used limited precision of the coefficients).
Lee[4] developed a modified form of the Antoine equation that allows for calculating vapor pressure across the entire temperature range using the acentric factor (𝜔) of a substance.