  A fully implicit phase field model has been implemented in Fortran for 1-3D
simulations. It is intended for simulations of diffusion and diffusion
controlled transformations. Gibbs energy contributions from both gradients in
concentration and gradients in phase field variables are included. Orientation
dependent interfacial energy is also supported. The implementation supports the
use of Calphad type databases as well as analytical Gibbs energy expressions,
though in the latter case phases may not have internal degrees of freedom.
