If my memory still works ZPE with that kind of basis sets are extremely demanding on terms of computing resources, memory and computing power. What computer hardware-software do you plan to use: Mac, Linux, Windows, Beowulf or AppleSeed cluters or a Cray (ernst question!)...

Yes indeed. Computer time is demanding. Am using Gaussian 16 in Linux.

Is it mandatory to use Minessota Local Functionals with the given basis sets?

If not, other methods where hessian is calculated much faster are available. For some of them, no scaling is necessary or the scaling factors are given.

For example, xtb can be used to calculate the hessian using GFN1-xTB or GFN2-xTB method, which is really fast. GFNFF is even faster.

https://xtb-docs.readthedocs.io/en/latest/setup.html

Regards,

Conrad

Thank you Conrad, but I've been using the Minnesota functionals for quiet a but if my work and it seems there are no scaling factors for the 2015 Minnesota local with these basis sets but if there is any, i would love to know. Thank you

I suppose, there are different types of these functionals available, with some containing Hartree-Fock exchange and some not. In case of those functionals having Hartree-Fock, there is a good chance, that not scaling is necessary, equally like for BLYP and PBE. If you chose the pure DFT functionals, you should be fine then.