	This is part of the ves module
	It is only available if you configure PLUMED with ./configure –enable-modules=ves . Furthermore, this feature is still being developed so take care when using it and report any problems on the mailing list.

Dummy optimizer for debugging.

This is dummy optimizer that can be used for debugging. It will not update the coefficients but can be used to monitor the gradient and Hessian for a given VES bias.

Description of components

By default the value of the calculated quantity can be referenced elsewhere in the input file by using the label of the action. Alternatively this Action can be used to calculate the following quantities by employing the keywords listed below. These quantities can be referenced elsewhere in the input by using this Action's label followed by a dot and the name of the quantity required from the list below.

Quantity	Keyword	Description
gradrms	MONITOR_INSTANTANEOUS_GRADIENT	the root mean square value of the coefficient gradient. For multiple biases this component is labeled using the number of the bias as gradrms-#.
gradmax	MONITOR_INSTANTANEOUS_GRADIENT	the largest absolute value of the coefficient gradient. For multiple biases this component is labeled using the number of the bias as gradmax-#.
avergradrms	MONITOR_AVERAGE_GRADIENT	the root mean square value of the averaged coefficient gradient. For multiple biases this component is labeled using the number of the bias as gradrms-#.
avergradmax	MONITOR_AVERAGE_GRADIENT	the largest absolute value of the averaged coefficient gradient. For multiple biases this component is labeled using the number of the bias as gradmax-#.

Compulsory keywords

BIAS	the label of the VES bias to be optimized
STRIDE	the frequency of updating the coefficients given in the number of MD steps.
COEFFS_FILE	( default=coeffs.data ) the name of output file for the coefficients
COEFFS_OUTPUT	( default=100 ) how often the coefficients should be written to file. This parameter is given as the number of iterations.

Options

MONITOR_INSTANTANEOUS_GRADIENT	( default=off ) if quantities related to the instantaneous gradient should be outputted.
MULTIPLE_WALKERS	( default=off ) if optimization is to be performed using multiple walkers connected via MPI
MONITOR_AVERAGE_GRADIENT	( default=off ) if the averaged gradient should be monitored and quantities related to it should be outputted.
MONITOR_HESSIAN	( default=off ) also monitor the Hessian
COEFFS_FMT	specify format for coefficient file(s) (useful for decrease the number of digits in regtests)
COEFFS_SET_ID_PREFIX	suffix to add to the filename given in FILE to identify the bias, should only be given if a single filename is given in FILE when optimizing multiple biases.
INITIAL_COEFFS	the name(s) of file(s) with the initial coefficients
TARGETDIST_AVERAGES_FILE	the name of output file for the target distribution averages. By default it is targetdist-averages.data.
TARGETDIST_AVERAGES_OUTPUT	how often the target distribution averages should be written out to file. Note that the value is given in terms of coefficient iterations. If no value is given are the averages only written at the beginning of the optimization
BIAS_OUTPUT	how often the bias(es) should be written out to file. Note that the value is given in terms of coefficient iterations.
FES_OUTPUT	how often the FES(s) should be written out to file. Note that the value is given in terms of coefficient iterations.
FES_PROJ_OUTPUT	how often the projections of the FES(s) should be written out to file. Note that the value is given in terms of coefficient iterations.
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
MONITOR_AVERAGES_GRADIENT_EXP_DECAY	use an exponentially decaying averaging with a given time constant when monitoring the averaged gradient

Examples

In the following input we use the OPT_DUMMY to monitor the gradient and Hessian for a given VES bias every 1 iteration.

phi:   TORSION ATOMS=5,7,9,15

bf1: BF_FOURIER ORDER=5 MINIMUM=-pi MAXIMUM=pi

VES_LINEAR_EXPANSION ...
 ARG=phi
 BASIS_FUNCTIONS=bf1
 LABEL=ves1
 TEMP=300.0
 GRID_BINS=100
... VES_LINEAR_EXPANSION

OPT_DUMMY ...
  BIAS=ves1
  STRIDE=1000
  LABEL=o1
  MONITOR_HESSIAN
  GRADIENT_FILE=gradient.data
  GRADIENT_OUTPUT=1
  GRADIENT_FMT=%12.6f
  HESSIAN_FILE=hessian.data
  HESSIAN_OUTPUT=1
  HESSIAN_FMT=%12.6f
... OPT_DUMMY