Theoretical chemist David Limmer was born in 1986 in Clovis, NM, a town of about 40,000 people in the far eastern part of the state, nine miles from the border with Texas.
“Clovis culture” refers to a Paleoamerican group that is credited with giving rise to many later Native American peoples. The opportunity to study Clovis culture at the Blackwater Draw site lured Limmer’s father from New York to an archeology program at Eastern New Mexico University in nearby Portales. There he met Limmer’s mother, who was from an old homestead family that had lived in the area for decades.
Limmer excelled in math and chemistry in high school, graduating in 2004. For college, he attended the New Mexico Institute of Mining and Technology in Socorro, about 80 miles south of Albuquerque. There he worked with John McCoy, who had earned his Ph.D. with the late theoretical chemist David Chandler at Berkeley.
Says Limmer, “In my third semester I needed some advanced classes that weren’t going to be offered, so I spent nine months Snapshot from a molecular dynamics simulation of an excess charge in a hybrid organic-inorganic perovskite lattice. The charge shown with a red tint in center forms a polaron in the hybrid perovskite lattice. DL David Limmer at Los Alamos National Laboratory where I measured gas flows through polymers. That’s where I discovered I wasn’t meant to be an experimentalist. I had much better luck applying statistical mechanics models to the problem.”
Limmer graduated summa cum laude from New Mexico Tech in 2008 with a B.S. in chemical engineering. As the top graduating senior, he won the campus’s Brown Award that year. In the fall he began his Ph.D. studies with Chandler in the College of Chemistry.
Limmer completed his thesis with Chandler in 2013. Following a brief transitional postdoc at LBNL, he moved to Princeton University for a second postdoc at the Center for Theoretical Studies. He returned to Berkeley and joined the faculty as an assistant professor in 2016.
Working with colleague Naomi Ginsberg, Limmer is currently exploring an interesting phenomenon of perovskite materials. Synthetic perovskites can be created with a mixture of the halides bromine and iodine that allow their properties to be “tuned,” making them useful for photovoltaic cells and other optoelectronic devices.
Says Limmer, “Imagine you are sitting in a dimly lit restaurant where you notice the vinaigrette salad dressing seems to be very well mixed. To get a better view, you shine your cell phone flashlight on the bottle, which causes the oil and vinegar to completely separate. Surprised, you turn off the light, only to see the vinaigrette return to being well mixed.
“That is pretty strange behavior, yet that is what the Ginsberg lab observed in their perovskite materials. If you shine a light on them, the mixed halide ions shift around the lattice until they are separated. This is not useful behavior in a PV material, but might be very useful in constructing optical switches and other sensors.”
The Ginsberg and Limmer groups have been working together to explore the basis for this odd perovskite behavior. “This work is an example of a nonequilibrium process with practical importance,” says Limmer, “which more generally is what my group is exploring here at Berkeley.”