I have already an optimized geometry and frequency calculation in both ground state and excited state as well (normal modes are not save in the check point file) by using DFT methods in Gaussian 16. How to run vibronic calculation for emission from these calculations without wasting much time . I know the keyword opt Freq=FC can be used to run these calculations but i I do not want to repeat optimization and frequency (the whole ) calculation again
It would be also great to know How to just save normal modes to the check point files without repeating these calculations ?
In addition, if someone can share any information about the input or keywords to calculate and save the real (absolute) coordinate of displacement vector (in cartesian coordinate ) of harmonic modes obtained from frequency calculations from Gaussian in order to know the magnitude of vibration corresponding to different vibration.
thanks