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Short helpfile for action METAD
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The following arguments are compulsory: 

                  SIGMA - the widths of the Gaussian hills 
                   PACE - the frequency for hill addition 
                   FILE - ( default=HILLS ) a file in which the list of added hills 
                          is stored 

In addition you may use the following options: 

  NUMERICAL_DERIVATIVES - ( default=off ) calculate the derivatives for these 
                          quantities numerically 
               CALC_RCT - ( default=off ) calculate the \f$c(t)\f$ reweighting factor 
                          and use that to obtain the normalized bias 
                          [rbias=bias-rct].This 
            GRID_SPARSE - ( default=off ) use a sparse grid to store hills 
          GRID_NOSPLINE - ( default=off ) don't use spline interpolation with grids 
            STORE_GRIDS - ( default=off ) store all the grid files the calculation 
                          generates. They will be deleted if this keyword is not present 
            WALKERS_MPI - ( default=off ) Switch on MPI version of multiple walkers - 
                          not compatible with WALKERS_* options other than WALKERS_DIR 
        FLYING_GAUSSIAN - ( default=off ) Switch on flying Gaussian method, must be 
                          used with WALKERS_MPI 
           ACCELERATION - ( default=off ) Set to TRUE if you want to compute the 
                          metadynamics acceleration factor. 
          CALC_MAX_BIAS - ( default=off ) Set to TRUE if you want to compute the 
                          maximum of the metadynamics V(s, t) 
   CALC_TRANSITION_BIAS - ( default=off ) Set to TRUE if you want to compute a 
                          metadynamics transition bias V*(t) 
     FREQUENCY_ADAPTIVE - ( default=off ) Set to TRUE if you want to enable frequency 
                          adaptive metadynamics such that the frequency for hill addition to 
                          change dynamically based on the acceleration factor. 
                    ARG - the input for this action is the scalar output from one or 
                          more other actions. The particular scalars that you will use are 
                          referenced using the label of the action. If the label appears on its 
                          own then it is assumed that the Action calculates a single 
                          scalar value. The value of this scalar is thus used as the input 
                          to this new action. If * or *.* appears the scalars calculated 
                          by all the proceeding actions in the input file are taken. 
                          Some actions have multi-component outputs and each component of 
                          the output has a specific label. For example a \ref DISTANCE 
                          action labelled dist may have three components x, y and z. To take 
                          just the x component you should use dist.x, if you wish to take 
                          all three components then use dist.*.More information on the 
                          referencing of Actions can be found in the section of the manual on the 
                          PLUMED \ref Syntax. Scalar values can also be referenced using 
                          POSIX regular expressions as detailed in the section on \ref 
                          Regex. To use this feature you you must compile PLUMED with the 
                          appropriate flag. You can use multiple instances of this keyword i.e. 
                          ARG1, ARG2, ARG3... 
                 HEIGHT - the heights of the Gaussian hills. Compulsory unless TAU 
                          and either BIASFACTOR or DAMPFACTOR are given 
                    FMT - specify format for HILLS files (useful for decrease the 
                          number of digits in regtests) 
             BIASFACTOR - use well tempered metadynamics and use this bias factor. 
                          Please note you must also specify temp 
                   RECT - list of bias factors for all the replicas 
             DAMPFACTOR - damp hills with exp(-max(V)/(\f$k_B\f$T*DAMPFACTOR) 
           TTBIASFACTOR - use transition tempered metadynamics with this bias factor. 
                          Please note you must also specify temp 
        TTBIASTHRESHOLD - use transition tempered metadynamics with this bias 
                          threshold. Please note you must also specify TTBIASFACTOR 
                TTALPHA - use transition tempered metadynamics with this hill size 
                          decay exponent parameter. Please note you must also specify 
                          TTBIASFACTOR 
                 TARGET - target to a predefined distribution 
                   TEMP - the system temperature - this is only needed if you are 
                          doing well-tempered metadynamics 
                    TAU - in well tempered metadynamics, sets height to (\f$k_B 
                          \Delta T\f$*pace*timestep)/tau 
               GRID_MIN - the lower bounds for the grid 
               GRID_MAX - the upper bounds for the grid 
               GRID_BIN - the number of bins for the grid 
           GRID_SPACING - the approximate grid spacing (to be used as an alternative 
                          or together with GRID_BIN) 
            RCT_USTRIDE - the update stride for calculating the \f$c(t)\f$ 
                          reweighting factor.The 
           GRID_WSTRIDE - write the grid to a file every N steps 
             GRID_WFILE - the file on which to write the grid 
             GRID_RFILE - a grid file from which the bias should be read at the 
                          initial step of the simulation 
               ADAPTIVE - use a geometric (=GEOM) or diffusion (=DIFF) based hills 
                          width scheme. Sigma is one number that has distance units or time 
                          step dimensions 
             WALKERS_ID - walker id 
              WALKERS_N - number of walkers 
            WALKERS_DIR - shared directory with the hills files from all the walkers 
        WALKERS_RSTRIDE - stride for reading hills files 
               INTERVAL - one dimensional lower and upper limits, outside the limits 
                          the system will not feel the biasing force. 
              SIGMA_MAX - the upper bounds for the sigmas (in CV units) when using 
                          adaptive hills. Negative number means no bounds 
              SIGMA_MIN - the lower bounds for the sigmas (in CV units) when using 
                          adaptive hills. Negative number means no bounds 
     ACCELERATION_RFILE - a data file from which the acceleration should be read at 
                          the initial step of the simulation 
         TRANSITIONWELL - This keyword appears multiple times as TRANSITIONWELL 
                          followed by an integer. Each specifies the coordinates for one well 
                          as in transition-tempered metadynamics. At least one must be 
                          provided. You can use multiple instances of this keyword i.e. 
                          TRANSITIONWELL1, TRANSITIONWELL2, TRANSITIONWELL3... 
    FA_UPDATE_FREQUENCY - the frequency for updating the hill addition pace in 
                          frequency adaptive metadynamics, by default this is equal to the 
                          value given in PACE 
            FA_MAX_PACE - the maximum hill addition frequency allowed in frequency 
                          adaptive metadynamics. By default there is no maximum value. 
    FA_MIN_ACCELERATION - only update the hill addition pace in frequency adaptive 
                          metadynamics after reaching the minimum acceleration factor given here. 
                          By default it is 1.0. 
                RESTART - allows per-action setting of restart (YES/NO/AUTO) 
            UPDATE_FROM - Only update this action from this time 
           UPDATE_UNTIL - Only update this action until this time 


