GeoPS: An interactive visual computing tool for thermodynamic modelling of phase equilibria

The availability of thermodynamic data for geologically relevant phases has made practical the calculation of stable phase relations throughout the mantle and crust of terrestrial planets. GeoPS () is a program designed for this purpose in which both input and output are done through an intuitive graphical user interface. GeoPS provides a wide range of phase equilibrium calculations based on a novel Gibbs energy minimization algorithm. The algorithm provides for exceptionally robust and computationally efficient solution to the phase equilibrium problem by successive alternation between a linear programming step to identify stable phase compositions and a non-linear programming step to refine the compositions estimated during the linear programming. Applications include calculation of various types of phase diagrams and path-dependent phase fractionation. By combining an easy-to-use graphical user interface with a robust and efficient solver, GeoPS makes phase equilibrium modelling accessible to researchers and students with minimal training and provides a powerful tool for understanding natural phase relations and for planning experimental work.