I am trying to use the fchk produced by Q-chem to perform the NBO calculations in Gaussian (these are very specific calculations and cannot be done using Q-chem and NBO7 code). I have two questions:
(1) During the SP calculations in Q-chem (GUI=2) two fchk files are generated - *.FChk and *.0.FChk or *.1.FChk. Which one contains the converged orbitals/wavefunction?
(2) Sometimes, when i use unfchk tool from gaussian and use the resulting unformated checkpoint to perform e.g. population analysis in gaussian [ # Guess(Read,Only) ChkBasis Geom(AllCheckpoint) Pop(NBO7Read) ] it works perfectly reproducing the numbers from native Q-chem+NBO7 calculations, but sometimes there is a clear problem with the basis set transformations and I simply cannot re-use fchk from Q-chem (cubegen on such fchk files produces absurd results). Do you know if there is a way to ensure that Gaussian is using the exact orbitals/wavefunction from Q-chem calculations? Maybe i should go with external basis sets?
Thank you in advance!