Mulliken charge¶

The Mulliken charge CV is defined as the sum over all partial Mulliken charges of a group of atoms $j,k,l,...$

$Q = \sum_{i=j,k,l,...} q_i.$

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

"collective variables": [
  {
    "type": "mullcharge",
    "name": "sum of mulliken charges of a group of atoms",
    "atoms": [j, k, l, ...],
    "iface": "dftbaby",
    "method": "analytic",
    "nproc": 1
  },
  ...
]

A list of atom indices is handed to the "atoms" keyword. At the moment, the Mulliken charge CV is only compatible with DFTBaby or Turbomole, so the only other possibility for the "iface" keyword is:

"iface": "turbomole"

Gradients can be calculated analytically if "method" is provided as shown above (only DFTBaby). If instead it is set to

"method": "numeric"

they will be calculated numerically. The number of processors to be used for the numeric evaluation is defined with "nproc".