The dynamical shell model was not designed to work with neutral
groups. This error results if an attempt is made to combine both.
Action:
There is no general remedy for this error if you wish to
combine both these capabilities. However if your simulation does not
require the polarisability to be a feature of rigid species
(comprising the charged groups), but
is confined to free atoms or flexible molecules in the same system,
you may consider overriding this error message and continuing with
your simulation. The appropriate error trap is found in subroutine
SYSDEF.