Why isn't CASPT2 used in surface hopping simulations?

I will write what I think the answer is. I'd like someone to confirm and maybe explain in detail.


I think that since surface hopping dynamics simulates movements on PES, it has to calculate gradients in each step. Since gradient for CASPT2 method can be evaluated only numericaly, CASPT2 quantum mechanical base for surface hopping dynamics would make calculations imspossibly slow. 


Is this correct?


