Energy gap¶

The energy gap between two electronic states $i,j$ is defined by the difference of their energies

$\Delta E = E_j-E_i$

The use of the energy gap is invoked by the following block in the meta-config.json file:

"collective variables": [
  {
    "type": "energygap",
    "name": "energy gap between two states",
    "state1": i,
    "state2": j,
    "do_multistate": False
  },
  ...
]

The "state1" and "state2" keywords set the electronic state indices to be used. This requires that the calculator provides energies and gradients for both states. Currently, the energygap CV can only be used in combination with the Molpro interface.

The Multistate Metadynamics extension is used, when "do_multistate" is set to True. In this case, the configuration for a second metadynamics instance has to be provided under the "metadynamics_multistate" keyword in the meta-config.json file.