I want to find a correct charge distribution of amines . I found that solvation model (SM8) has correct charge distribution .how can I use this solvation model in gaussview and gaussian ?
There is no reason to use SM8 in Gaussian. First, Gaussian doesn't support SM8; second, the SMD has more rigorous theoretical foundation than SM8. SMD is fully able to reasonably exhibit influence on charge distribution of amines caused by solvent environment.
To best of my knowledge SM8 is not available with Gaussian(https://comp.chem.umn.edu/solvation/). You can use SMD instead. SM8 is available with Qchem, Jaguar, Spartan, etc (Please check the above webpage). Although I cannot comment on the performance difference between SMD and SM8 for your systems. I hope someone who has more expertise in the field will include further clarification regarding that.
There is no reason to use SM8 in Gaussian. First, Gaussian doesn't support SM8; second, the SMD has more rigorous theoretical foundation than SM8. SMD is fully able to reasonably exhibit influence on charge distribution of amines caused by solvent environment.
Gaussian has SMD solvation model (that is based on SM8). For gaussian, SMD may be a good option to apply a continuum model of the solvent, most times being better than the former one, according to J. Phys. Chem. B 2009, 113, 18, 6378-6396.