I am mainly an experimental chemist, and use theory to compliment experimental results (so for the guru's out there, go easy on me, haha!). Over the years, I have been trying to teach myself the basics of the theory I need in order to do the calculations I need, which has been very frustrating at times and very fruitful in others!

Anyways, the latest calculations I am trying to do is a TD-DFT calculation to calculate the transition energies and oscillator strengths in a Cu(I) transition-metal dimer complex that has a halogen bridge between the two moieties of the dimer (not the easiest molecule to begin with, I know!!). The command line for my input file is as shown below:

#p TD=(NStates=10,50-50,Direct)/gen Density=Current GFINPUT Pop=(NBO,FULL) nosymm

my questions are these:

1) where in the calculation input do I indicate, if I even do or can, the functional I used for the previous geometry optimization? does this sort of TD-DFT calculation even need/account for specific functionals or does it only require basis set inputs?

2) are TD-DFT transition energies, etc...meaningless if calculated with a different basis set than the previously calculated geometry optimization whose coordinates are used as the input for the TD-DFT calculation?

3) when calculating molecular orbitals (with the Pop=(NBO,FULL) command) are these orbitals more "trustworhty" when done in the TD-DFT calculation as above, or as part of the ground state geometry optimization?

Thanks in advance for any insight and help anyone can give into these issues