David's formal training and early research was in computational chemistry, including postdoctoral research in which he was one of the original developers of the NWChem parallel computational chemistry package. Later, he transitioned his research program to computer science, allowing him to work more broadly on some of the challenges he first encountered as a developer of large-scale scientific software for high-end computers. Since then, his research has involved software environments for scientific computing, broadly interpreted, including programming systems, software architecture and software engineering, and other areas. In addition to his research activities in the Computer Science and Mathematics Division, David also leads the team responsible for the Programming Environment and Tools for the Oak Ridge Leadership Computing Facility (OLCF).