ABSTRACT
To predict how a photosynthetic protein tunes the spectral and redox properties of chlorophyll pigments is of fundamental importance in order to understand its light-harvesting properties. Specific pigment–protein interactions shift the energy levels of the chlorophylls, thus defining the energy ladder—the pathways—for energy and electron transfer. In this chapter, we overview the basic computational methods rooted on quantum chemistry and classical electrostatics that can be applied in order to calculate spectral and redox properties of chlorophylls in a protein environment, ranging from simple estimates based on the calculation of frontier molecular orbitals to advanced methodologies based on density functional theory. In order to include the key effect of the surrounding protein on the pigment properties, we describe how these quantum chemistry methods can be coupled to a simpler classical description of the environment, based on either classical force fields or continuum solvation models.
