Using Scaled Nuclear Charges
One can scale (uniformly) the nuclear charges of all atoms in a molecule by including the following somewhere in the ZMAT file:
if this record is found, all nuclear charges will be scaled by the factor x.xx. Such calculations can be useful in finding energies of temporary anions by plotting the electron affinity of the (bound) states of the system with extra nuclear charge v. the scaling factor.
If the ZSCALEEXP=ON keyword is set, this directive will also result in a uniform scaling (by the factor specified as above squared) of the exponents in the basis set.