Energy is passed correctly

It is common practise to use the potential energy as a collective energy. Some MD codes thus pass the potential energy to PLUMED. To check that this quantity has been passed correctly we can output the passed energy from PLUMED using the following input.

Click on the labels of the actions for more information on what each action computes
tested on2.10
tested onmaster
e: 
ENERGY
Calculate the total potential energy of the simulation box. More details
 

PRINT
Print quantities to a file. More details
 
ARG
the labels of the values that you would like to print to the file
=e 
FILE
the name of the file on which to output these quantities
=colvar

We can then also output the energy from the MD code and check this matches the value output by PLUMED. We run a short trajectory to test that the energy is passed correctly.

Trajectory

Input and output files for the test calculation are available inthis zip archive

Results

MD code output PLUMED output Tolerance % Difference
-18174.695312 0.0 0.001 1817469531.1999998
-18171.693359 0.0 0.001 1817169335.9
-18191.867188 0.0 0.001 1819186718.8000002
-18159.671875 0.0 0.001 1815967187.5
-18140.642578 0.0 0.001 1814064257.7999997
-18116.839844 0.0 0.001 1811683984.3999996
-18095.095703 0.0 0.001 1809509570.2999997
-18081.96875 0.0 0.001 1808196875.0
-18080.583984 0.0 0.001 1808058398.4
-18089.1875 0.0 0.001 1808918750.0
-18102.207031 0.0 0.001 1810220703.1000004
-18113.455078 0.0 0.001 1811345507.7999997
-18120.054688 0.0 0.001 1812005468.8000002
-18124.757812 0.0 0.001 1812475781.1999998
-18133.689453 0.0 0.001 1813368945.2999997
-18151.011719 0.0 0.001 1815101171.8999996
-18174.0 0.0 0.001 1817400000.0
-18193.904297 0.0 0.001 1819390429.7000003
-18201.589844 0.0 0.001 1820158984.3999996
-18193.394531 0.0 0.001 1819339453.1

The table below includes some of the results from the calculation. The columns contain:

  1. The energies that were obtained from the MD code, $x_{md}$.
  2. The energies that were obtained from PLUMED, $x_{pl}$.
  3. The tolerances that were used when comparing these quantities, $\delta$.
  4. The values of $100\frac{\vert x_{md} - x_{pl}\vert }{ \delta }$.

If the PLUMED interface is working correctly the first two sets of numbers should be identical and the final column should be filled with zeros.

Graphical representation (beta)

A visualization of the table above:
energy_master