Mukamel visualizes these nested commutators as (ket and bra evolve separately). For third-order, there are exactly 5 distinct diagrams that survive in the rotating wave approximation:
The guide breaks down how we observe molecular action in "real time" (femtoseconds) using several key pillars: A Practical Approach or: Mukamel for Dummies Mukamel visualizes these nested commutators as (ket and
is the response function . That is the molecule telling you: “I remember what you did to me at ( t_1 ), ( t_2 ), and ( t_3 ).” ( t_2 )
Here is the practical punchline: