Tomorrow I am visiting the Solid State and Structural Chemistry Unit at the Indian Institute of Science in Bangalore. My host in Ramasesha. I will give a talk [slides] about effective Hamiltonians for the excited electronic states of methine dyes (including the chromophore for the Green Fluorescent Protein). All of this work was done largely by Seth Olsen.
A good introduction and overview is our recent J. Chem. Phys. paper.