gem for Windows is an upgrade version of gem for DOS.
gem stands for Gibbs Energy Minimizer and designed to calculate chemical equilibria using MALT data.
There are two calculation modes corresponding to the energy to be minimized, Gibbs mode (to minimize the gibbs energy of the chemical system upon consideration) and Helmholtz mode (helmholtz energy).
gem calculates the equilibrium point by unique convergent algorithm* mainly based on gradient projection method and backed up by some idea of linear programming.
* T.Matsumoto and H.Yokokawa, Netsu Sokutei, 19(4)(1992)170-173(in Japanese).
The algorithm in English can be seen in gemManual.pdf in CD-ROM, or at www.kagaku.com/malt .