It allows the prediction of vertical transitions from classical turning points, and assumes that nuclear locations do not change until after their electrons have adopted their final distributions.
The primary use of this principle is in making band assignments and deducing the relative shapes of two different electronic states. It allows the prediction of vertical transitions from classical turning points, and assumes that nuclear locations do not change until after their electrons have adopted their final distributions. An extension of the Born-Oppenheimer approximation, FTP, name this principle which states that in fast reactions such as transitions of electron states, there is no time for geometry to change.
The primary use of this principle is in making band assignments and deducing the relative shapes of two different electronic states.
Franck-Condon principle