Class of 2007
Ed Hohenstein
Graduate Student Works in Quantum Chemistry
In his off hours, Ed enjoys fishing, a pastime he and Professor Rick Locker shared at WC.
As a Ph.D. candidate in computational chemistry at Georgia Tech, Ed Hohenstein '07 is part of a research group that applies the principles of quantum mechanics to better model and understand chemical phenomena, from bond-breaking reactions to non-covalent interactions. Under the direction of Professor David Sherrill, Ed and his colleagues are studying the fundamental forces of molecular recognition (including -Π, CH/Π, SH/Π, etc., interactions) to determine their strength, geometric dependence and substituent effects. These questions are foundational for rational drug design or crystal engineering. The Sherrill Group's work on Π-Π interactions was featured on the May 2008 cover of Physical Chemistry Chemical Physics.
A double major in chemistry and mathematics at WC, Ed worked with chemistry professor Rick Locker for both his summer research project and his senior capstone. "My summer project looked at the acid-base behavior of 2,3-diaminophenazine," Ed recalls. "I used some computational techniques (mainly density functional theory) to determine where this molecule would protonate. I then used time-dependant density-functional theory to compute theoretical UV-Vis spectra of the protonated complexes. The second half of the project was an experimental verification of my computational results. I looked at the behavior of PH-dependant UV-Vis spectra of model complexes for 2,3-diaminophenazine."
For his senior project, Ed examined the kinetics of the chemical oxidation of o-phenylenediamine to 2,3-diaminophenazine and 3-aminophenaz-2-ol. "The math component was the numerical modeling of the kinetics using the Runge-Kutta-Fehlberg algorithm to approximate solutions to the system of differential equations governing the reactions. I used UV-Vis spectroscopy to follow the progress of the reaction and fit the data numerically. We showed that a mechanism proposed in the literature could not be correct."
In his lab at Georgia Tech, Ed is studying noncovalent interactions in biologically relevant model systems using highly accurate quantum chemical methods, mainly coupled cluster theory and Moller-Plesset perturbation theory. He also has been working on developing approximate methods that will help reduce computational expense. Collaborating with an experimental group, Ed is looking at the bond-breaking of CaH+ using equation-of-motion coupled cluster in order to help them determine the laser frequency they will need to use to excite a certain transition.
Ed hasn't yet decided what he wants to do after he earns his Ph.D., but he says "a job at a national lab or in academia seems appealing."
Check out his team's work at http://vergil.chemistry.gatech.edu/