Release64:Qmmm mm charges

From NWChem

mm_charges [exclude <(none||all||linkbond||linkbond_H) default none>]
           [expand  <none||all||solute||solvent> default none]
           [update  <integer default 0>]

This directive controls treatment of classical point (MM) charges that are interacting with QM region. For most QM/MM applications the use of directive will be not be necessary. Its absence would be simply mean that all MM charges within the cuttof distance ( as specified by cutoff ) as well those belonging to the charges groups directly bonded to QM region will be allowed to interact with QM region.

Keyword exclude specifies the subset MM charges that will be specifically excluded from interacting with QM region.

• none default value reverts to the original set of MM charges as described above.
• all excludes all MM charges from interacting with QM region ("gas phase" calculation).
• linkbond excludes MM charges that are connected to a quantum region by at most two bonds,
• linkbond_H similar to linkbond but excludes only hydrogen atoms.

Keyword expand expands the set MM charges interacting with QM region beyond the limits imposed by cutoff value.

• none default value reverts to the original set of MM charges
• solute expands electrostatic interaction to all solute MM charges
• solvent expands electrostatic interaction to all solvent MM charges
• all expands electrostatic interaction to all MM charges

Keyword update specifies how often list of MM charges will be updated in the course of the calculation. Default behavior is not to update.