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David Keffer

I Experiment, Therefore I Compute – David Keffer

by Theresa Pepin

Experimentation and computation are inextricably linked in many if not most research projects of our time. But what is critical to success—and far less obvious—is how essential communication becomes among members of an interdisciplinary team who engage in this joint enterprise. Number-crunching modelers can only simulate and accurately compare data if they understand the experimentation of their colleagues.

David Keffer and his computational team provide experimentalists at ORNL with proven, molecular-level guidance to understanding the fundamental relationship between nanostructure and lithium-ion conductivity in new lignin-based carbon fiber anodes. Lignin is the organic, renewable substance that along with cellulose provides rigidity in the cell walls of plants.

keffer_sns_nomad_2Their tool of choice is a high-performance computing tool kit they have built, tested, and now employ in an integrated suite for multiscale modeling. (The challenge for modelers in exploring structure-property relationships from materials is to effectively employ multiscale modeling techniques incorporating four scales of “description”—the quantum scale in which electron distributions are important; the molecular scale in which the distribution of atoms and molecules is important; the mesocale in which the larger clusters of molecules are important; and macro-scale in which the material is treated as a continuum.)

The demonstrated ability to integrate multiple levels of modeling into a coherent, dynamic rendering of the structure-property relationship is a unique hallmark of Keffer’s Computational Materials Research Group.

While the corresponding LDRD project, led by Orlando Rios at ORNL, directly benefits from the modeling results of Keffer’s team, the project collaboration gives the JDRD team the opportunity to expand its range of applications into the strategically important area of high-capacity, low-cost, renewable-source batteries. The goal for both teams is to achieve a fundamental understanding that will allow for the fabrication and production of a revolutionary new anode material for applications such as battery packs in hybrid-electric and fully electric vehicles.

keffer_sns_nomad_4

Keffer’s students have been especially excited to have the opportunity of hands-on familiarity with the LDRD experiments at the NOMAD beam line of the Spallation Neutron Source at ORNL. More generally, lessons learned in communication skills and in how to acquire cross-disciplinary subject expertise serve to prepare students to be team members in developing applications in other fields of study.

keffer_sns_nomad_3For his part, Rios reports that Keffer’s modeling and computational work has been so integral to the experimentation process that their combined effort has become a truly synergistic approach to modeling and synthesis.  Going well beyond the simple comparison of model and data, the computational team has predicted results later proven experimentally.

You cannot get much better than that.

Progress to date has already led to substantive proposals jointly undertaken by the two teams. Also submitted for publication is an article by the JDRD team—including post doc Qifei Wang and graduate student Nick McNutt.


JDRD project:
Lignin-based high performance Li-ion anode materials synthesized from low-cost renewable resources (year 2)
David Keffer, UT Materials Science and Engineering Department

LDRD project:
Lignin-based high performance Li-ion anode materials synthesized from low-cost renewable resources
Orlando Rios, ORNL Materials Science and Technology Division