[theochem-announce] Theochem Seminar 4:00 PM TODAY @ HARVARD - Prof. Stefano Baroni

[Thomas Robert Avila]

Hello all,

Prof. Stefano Baroni from the International School for Advanced Studies (Trieste, Italy) will give a talk in the Theochem seminar series today at Harvard at 4:00 PM.

Prof. Baroni is known for pioneering different quantum simulation methods, among which the most widely known are density-functional-perturbation theory and reptation quantum Monte Carlo.

Title: "Ab-initio colors"
Speaker: Prof. Stefano Baroni
Date: Thursday, Oct 24th, 4.00-6.00pm 
Venue: Pfizer Lecture Hall (Mallinckrodt Building, 12 Oxford St., Cambridge)  - Harvard University 

-Thomas

Abstract:
I will present some recent work addressing the effects of the solvent (water) on the optical properties of natural dyes. I will break the ice with a short presentation of the physics and physiology of color vision, in the style of popular science. I will then introduce some of the theoretical and computational techniques that are currently being used to model the optical properties of complex molecular systems and nano- structured materials, based on time-dependent density-functional perturbation theory. These techniques will be demonstrated with the “prediction” that grass is green, and applied to the optical properties of flavylium, the die that gives aubergines and blueberries their typical deep-purple coloration, as well as of other anthocyanins. I will show that the main effect of the solvent is to provide a medium allowing thermal fluctuations to fill the gaps that would otherwise characterize the spectrum of the dye at low temperature, thus considerably enhancing optical absorption in the visible range, and making blueberries (deep) blue. The uncertainties due to the inadequacies of current energy functionals will be discussed, along with the prospects of predicting and engineering the color optical properties of anthocyanins in solution.