Determination of the isobar quality

Peacemaker performs \(a_{mf}\), \(b_{xv}\) parameter sampling on a grid, which can be specified in the [qce] section of the input file. For each pair, the quality of the resulting isobar is compared to certain experimental quantities. The following options are available for this purpose: single density, isobar, temperature of phase transition. The isobar quality is computed according to the following equation:

\[\mathrm{error} = w_\mathrm{density} \left(\frac{\rho - \rho^\mathrm{exp}}{\rho^\mathrm{exp}}\right)^2 + w_\mathrm{isobar} \frac{1}{N} \sum_{i=1}^{N} \left(\frac{V_i - V_i^\mathrm{exp}}{V_i^\mathrm{exp}}\right)^2 + w_\mathrm{phase\ transition} \left(\frac{T_\mathrm{pt} - T_\mathrm{pt}^\mathrm{exp}}{T_\mathrm{pt}^\mathrm{exp}}\right)^2\]

Any combination of the experimental data above can be chosen. The relative importance of each quantity can be specified by the weight \(w\).

Isobars are specified by an isobar file. This file shall contain two columns of numbers: temperatures in K in column one and volumes in \(\mathrm{dm^3}\) in column two. All temperatures must be within the temperature range specified in the [qce] section. There are no requirements on the order of the temperatures. Temperatures may be included multiple times to put special weight on them. If a reference temperature is not equal to the temperature specified by the temperature range in the [qce] section, linear interpolation between the two closest temperatures is performed.