  We show that one can employ well-established numerical continuation methods
to efficiently calculate the phase diagram for thermodynamic systems. In
particular, this involves the determination of lines of phase coexistence
related to first order phase transitions and the continuation of triple points.
To illustrate the method we apply it to a binary Phase-Field-Crystal model for
the crystallisation of a mixture of two types of particles. The resulting phase
diagram is determined for one- and two-dimensional domains. In the former case
it is compared to the diagram obtained from a one-mode approximation. The
various observed liquid and crystalline phases and their stable and metastable
coexistence are discussed as well as the temperature-dependence of the phase
diagrams. This includes the (dis)appearance of critical points and triple
points. We also relate bifurcation diagrams for finite-size systems to the
thermodynamics of phase transitions in the infinite-size limit.
