  Photosynthesis is a fundamental process for plants to produce energy and
survive. It is a well known fact that the light reactions in photosynthesis are
a significant part of the overall process, and are carried out by chlorophyll
molecules. This paper outlines the quantum chemical and mathematical
description concerning electronic state transitions that take place in
chlorophyll molecules during photosynthesis. In particular, the electronic
transition of chlorophylls is assumed as a diatomic rovibrational 0 --> 0
transition, and is mathematically described accordingly. Then, the correlation
of the Franck-Condon Principle in accordance to the photoexcitation of
chlorophylls is delineated. Finally, existing research concerning the concepts
laid out in this paper is discussed, and future implications of quantum
chemical theory concerning chlorophyll photoexcitation is discussed.
