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.
ALPHARMSD	Probe the alpha helical content of a protein structure.
ANGLE	Calculate an angle.
ANGLES	Calculate an angle.
ANGLE_SCALAR	Calculate an angle.
ANGLE_VECTOR	Calculate multiple angles.
ANTIBETARMSD	Probe the antiparallel beta sheet content of your protein structure.
BETWEEN_MATRIX	Transform all the elements of a matrix using a switching function that is oen when the input value is within a particular range
BOPS	Calculate the BOPS order parameter
CELL	Calculate the components of the simulation cell
COMBINE_MATRIX	Calculate the sum of a number of matrices
CONSTANT	Create a constant value that can be passed to actions
CONTACTMAP	Calculate the distances between a number of pairs of atoms and transform each distance by a switching function.
COORDINATION	Calculate coordination numbers.
CUSTOM_MATRIX	Calculate an arbitrary function piecewise for one or multiple input matrices.
DHENERGY	Calculate Debye-Huckel interaction energy among GROUPA and GROUPB.
DIHCOR	Measures the degree of similarity between dihedral angles.
DIHEDRAL_CORRELATION	Measure the correlation between a pair of dihedral angles
DIHEDRAL_CORRELATION_SCALAR	Measure the correlation between a multiple pairs of dihedral angles
DIHEDRAL_CORRELATION_VECTOR	Measure the correlation between a multiple pairs of 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.
DIPOLE_SCALAR	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.
DISTANCE_FROM_SPHERICAL_CONTOUR	Calculate the perpendicular distance from a Willard-Chandler dividing surface.
DOPS	Calculate the DOPS order parameter
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
GEOMETRIC_PATH	Distance along and from a path calculated using geometric formulas
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.
GPATH	Distance along and from a path calculated using geometric formulas
GPROPERTYMAP	Property maps but with a more flexible framework for the distance metric being used.
GSYMFUNC_THREEBODY	Calculate functions of the coordinates of the coordinates of all pairs of bonds in the first coordination sphere of an atom
GYRATION	Calculate the radius of gyration, or other properties related to it.
GYRATION_FAST	Calculate the radius of gyration, or other properties related to it.
HBPAMM_SA	Calculate the number of hydrogen bonds each acceptor participates in using the HBPamm method
HBPAMM_SD	Calculate the number of hydrogen bonds each donor participates in using the HBPamm method
HBPAMM_SH	Calculate the number of hydrogen bonds each hydrogen participates in using the HBPamm method
HIGHEST_SCALAR	Calculate the highest of a set of sclalar arguments
HIGHEST_VECTOR	Calculate the largest element in a vector of inputs
LESS_THAN_MATRIX	Transform all the elements of a matrix using a switching function that is one when the input value is smaller than a threshold
LOWEST_SCALAR	Calculate the lowest of a set of sclalar arguments
LOWEST_VECTOR	Calculate the lowest element in a vector of inputs
MATHEVAL_MATRIX	Calculate an arbitrary function piecewise for one or multiple input matrices.
MEAN	Calculate the arithmetic mean of the elements in a vector
MEAN_SCALAR	Calculate the arithmetic mean of the set of input scalars
MEAN_VECTOR	Calculate the arithmetic mean of the elements in a vector
MORE_THAN_MATRIX	Transform all the elements of a matrix using a switching function that is one when the input value is larger than a threshold
ONES	Create a constant vector with all elements equal to one
OUTER_PRODUCT	Calculate the outer product matrix of two vectors
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
PDB2CONSTANT	Create a constant value from a PDB input file
PLANE	Calculate the plane perpendicular to two vectors in order to represent the orientation of a planar molecule.
PLANE_SCALAR	Calculate the plane perpendicular to two vectors in order to represent the orientation of a planar molecule.
PLANE_VECTOR	Calculate the plane perpendicular to two vectors in order to represent the orientation of a planar molecule multiple times.
POSITION	Calculate the components of the position of an atom.
POSITION_SCALAR	Calculate the components of the position of an atom.
POSITION_VECTOR	Create a vector that holds the components of the position of a set of atoms.
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.
PYCVINTERFACE	Define collective variables in the Python language.
QUATERNION	Calculate quaternions for molecules.
QUATERNION_SCALAR	Calculate a single quaternion
QUATERNION_VECTOR	Calculate multiple quaternions
READMASSCHARGE	Set the masses and charges from an input PDB file.
ROPS	Calculate the ROPS order parameter
SUM	Calculate the sum of the arguments
SUM_MATRIX	Sum all the elements in a matrix
SUM_SCALAR	Calculate the SUM of the set of input scalars
SUM_VECTOR	Calculate the sum of the elements in a vector
TEMPLATE	This file provides a template for if you want to introduce a new CV.
TORSION	Calculate a torsional angle.
TORSION_SCALAR	Calculate a torsional angle.
VOLUME	Calculate the volume of the simulation box.
XANGLES	Calculate the angle between an arbitrary vector and the positive x direction
XYTORSIONS	Calculate the torsional angle around the x axis between an arbitrary vector and the positive y direction
XZTORSIONS	Calculate the torsional angle around the x axis between an arbitrary vector and the positive z direction
YANGLES	Calculate the angle between an arbitrary vector and the positive y direction
YXTORSIONS	Calculate the torsional angle around the y axis between an arbitrary vector and the positive x direction
YZTORSIONS	Calculate the torsional angle around the y axis between an arbitrary vector and the positive z direction
ZANGLES	Calculate the angle between an arbitrary vector and the positive z direction
ZXTORSIONS	Calculate the torsional angle around the z axis between an arbitrary vector and the positive x direction
ZYTORSIONS	Calculate the torsional angle around the z axis between an arbitrary vector and the positive y direction

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.
EMMIVOX	(from PLUMED-ISDB module) Bayesian single-structure and ensemble refinement with cryo-EM maps.
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.
METATENSOR	(from Metatensor module) Use arbitrary machine learning models as collective variables.
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.
SHADOW	(from PLUMED-ISDB module) Communicate atoms positions among replicas and calculate the RMSD with respect to a mother (reference) simulation.
SIZESHAPE_POSITION_LINEAR_PROJ	(from sizeshape collective variable module) Calculates a linear projection in the space of a given reference configurational distribution in size-and-shape space.
SIZESHAPE_POSITION_MAHA_DIST	(from sizeshape collective variable module) Calculates Mahalanobis distance of a current configuration from a given reference configurational distribution in size-and-shape space.