virtual double GetPartialCharge() const
Return the floating point partial charge on an atom. The default
value is 0.0. The ``partial charge'' property on an atom may be set
using the OEAtomBase::SetPartialCharge method. The partial charge
property is a stored, not a calculated, property. The function
OEClearPartialCharges may be used to reset the partial charges on
a molecule to zero, and the function OEFormalPartialCharges may be
used to set the partial charge on each atom equal to its formal charge.