The following list contains descriptions of a number of the colvars that are currently implemented in PLUMED.

ADAPTIVE_PATH	Compute path collective variables that adapt to the lowest free energy path connecting states A and B.
ALPHABETA	Measures a distance including pbc between the instantaneous values of a set of torsional angles and set of reference values.
ALPHARMSD	Probe the alpha helical content of a protein structure.
ANGLE	Calculate an angle.
ANTIBETARMSD	Probe the antiparallel beta sheet content of your protein structure.
CELL	Calculate the components of the simulation cell
CONSTANT	Return one or more constant quantities with or without derivatives.
CONTACTMAP	Calculate the distances between a number of pairs of atoms and transform each distance by a switching function.
COORDINATION	Calculate coordination numbers.
DHENERGY	Calculate Debye-Huckel interaction energy among GROUPA and GROUPB.
DIHCOR	Measures the degree of similarity between dihedral angles.
DIMER	This CV computes the dimer interaction energy for a collection of dimers.
DIPOLE	Calculate the dipole moment for a group of atoms.
DISTANCE	Calculate the distance between a pair of atoms.
DISTANCE_FROM_CONTOUR	Calculate the perpendicular distance from a Willard-Chandler dividing surface.
EEFSOLV	Calculates EEF1 solvation free energy for a group of atoms.
ENERGY	Calculate the total potential energy of the simulation box.
ERMSD	Calculate eRMSD with respect to a reference structure.
EXTRACV	Allow PLUMED to use collective variables computed in the MD engine.
FAKE	This is a fake colvar container used by cltools or various other actions that supports input and period definitions
GHBFIX	Calculate the GHBFIX interaction energy among GROUPA and GROUPBusing a potential defined in Kührová et al., Improving the performance of the AMBER RNA force field bytuning the hydrogen-bonding interactions, JCTC, 2019. Essentially it is a switching function being -1 for small distances and 0 for large distances with a smooth interpolation in the middle. This can be scaled as desired by specifying interaction scaling parameters and energy units.
GPROPERTYMAP	Property maps but with a more flexible framework for the distance metric being used.
GYRATION	Calculate the radius of gyration, or other properties related to it.
PARABETARMSD	Probe the parallel beta sheet content of your protein structure.
PATH	Path collective variables with a more flexible framework for the distance metric being used.
PATHMSD	This Colvar calculates path collective variables.
PCAVARS	Projection on principal component eigenvectors or other high dimensional linear subspace
POSITION	Calculate the components of the position of an atom.
PROJECTION_ON_AXIS	Calculate a position based on the projection along and extension from a defined axis.
PROPERTYMAP	Calculate generic property maps.
PUCKERING	Calculate sugar pseudorotation coordinates.
TEMPLATE	This file provides a template for if you want to introduce a new CV.
TORSION	Calculate a torsional angle.
VOLUME	Calculate the volume of the simulation box.

In addition to the keywords above, by enabling optional modules you can access to the following keywords:

CS2BACKBONE	(from PLUMED-ISDB module) Calculates the backbone chemical shifts for a protein.
EMMI	(from PLUMED-ISDB module) Calculate the fit of a structure or ensemble of structures with a cryo-EM density map.
FRET	(from PLUMED-ISDB module) Calculates the FRET efficiency between a pair of atoms.The efficiency is calculated using the Forster relation:
FUNNEL_PS	(from Funnel-Metadynamics (FM) module) FUNNEL_PS implements the Funnel-Metadynamics (FM) technique in PLUMED 2.
FUSIONPOREEXPANSIONP	(from Membrane Fusion module) A CV for inducing the expansion of a fusion pore from a nucleated fusion pore.
FUSIONPORENUCLEATIONP	(from Membrane Fusion module) A CV for inducing the nucleation of the fusion pore from a hemifusion stalk.
JCOUPLING	(from PLUMED-ISDB module) Calculates 3J coupling constants for a dihedral angle.
MEMFUSIONP	(from Membrane Fusion module) Calculate a CV that can induce the formation of the hemifusion stalk between two initially flat and planar bilayers.
NOE	(from PLUMED-ISDB module) Calculates NOE intensities as sums of 1/r^6, also averaging over multiple equivalent atoms or ambiguous NOE.
PCS	(from PLUMED-ISDB module) Calculates the Pseudo-contact shift of a nucleus determined by the presence of a metal ion susceptible to anisotropic magnetization.
PIV	(from PIV collective variable module) Calculates the PIV-distance.
PRE	(from PLUMED-ISDB module) Calculates the Paramagnetic Resonance Enhancement intensity ratio between a spin label atom and a list of atoms .
RDC	(from PLUMED-ISDB module) Calculates the (Residual) Dipolar Coupling between two atoms.
S2CM	(from S2 contact model collective variable module) S2 contact model CV.
SANS	(from PLUMED-ISDB module) Calculates SANS intensity.
SASA_HASEL	(from SASA collective variable module) Calculates the solvent accessible surface area (SASA) of a protein molecule, or other properties related to it.
SASA_LCPO	(from SASA collective variable module) Calculates the solvent accessible surface area (SASA) of a protein molecule, or other properties related to it.
SAXS	(from PLUMED-ISDB module) Calculates SAXS intensity.