  PLUMED-GUI is an interactive environment to develop and test complex PLUMED
scripts within the Visual Molecular Dynamics (VMD) environment. Computational
biophysicists can take advantage of both PLUMED's rich syntax to define
collective variables (CVs) and VMD's chemically-aware atom selection language,
while working within a natural point-and-click interface. Pre-defined templates
and syntax mnemonics facilitate the definition of well-known reaction
coordinates. Complex CVs, e.g. involving reference snapshots used for RMSD or
native contacts calculations, can be built through dialogs that provide a
synoptic view of the available options. Scripts can be either exported for use
in simulation programs, or evaluated on the currently loaded molecular
trajectories. Development of scripts takes place without leaving VMD, thus
enabling an incremental try-see-modify development model for molecular metrics.
