DUMPDERIVATIVES

Dump the derivatives with respect to the input parameters for one or more objects (generally CVs, functions or biases).

For a CV this line in input instructs plumed to print the derivative of the CV with respect to the atom positions and the cell vectors (virial-like form). In contrast, for a function or bias the derivative with respect to the input "CVs" will be output. This command is most often used to test whether or not analytic derivatives have been implemented correctly. This can be done by outputting the derivatives calculated analytically and numerically. You can control the buffering of output using the FLUSH keyword.

Compulsory keywords

ARG	the input for this action is the output from one or more other actions. The particular output that you used is referenced using that action of interests label. If the label appears on its own then the value of the relevant Action is taken. If * or *.* appears the information from all arguments is taken. Some actions have multi-component outputs, each component of the output has a specific label so for instance an action labelled dist may have three componets 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.*
STRIDE	( default=1 ) the frequency with which the derivatives should be output
FILE	the name of the file on which to output the derivatives
FMT	( default=%15.10f ) the format with which the derivatives should be output

Examples

The following input instructs plumed to write a file called deriv that contains both the analytical and numerical derivatives of the distance between atoms 1 and 2.

DISTANCE ATOM=1,2 LABEL=distance
DISTANCE ATOM=1,2 LABEL=distanceN NUMERICAL_DERIVATIVES
DUMPDERIVATIVES ARG=distance,distanceN STRIDE=1 FILE=deriv

(See also DISTANCE)