Hi
I have question about using method and basis set for optimization:
Is it correct? for example I use hf/3-21g for optimization my molecule and after that I use optimize molecule and then put ( b3lyp/6-31g(d,p) pop=full) for calculate HOMO and LUMO energy?
Is it necessary to use same method and basis set for optimization and homo lumo ?
or not?
Actualy I want to report calculation numbers in my essay so I want to know it is common to optimise in different way than the rest of my other calculation as I talked about for example HOMO LUMO ?