David Halstead

Associate with SCL - AmesLab

University Education

Department of Chemistry, The University of Liverpool

1986-'90, PhD, Theoretical Surface Science
1985-'86, MSc, Theoretical Surface Science
1982-'85, BSc, Honours Chemistry

Research Interests

My early research was directed towards the investigation of quantum effects in the dynamics of atom and molecular collisions with metal surfaces. This involved the solution of the multi-dimensional, time dependant Schršdinger equation for scattering simulations of interactions where quantum effects such as tunneling, zero point energy and diffraction must be considered. These were compared with semi-classical trajectory simulations using Gaussian wavepackets. The results of this work were presented in the form of real time movies on a Macintosh computer to aid the comprehension of the large amounts of data produced. This research lead to a joint collaboration with the Technical University of Denmark with Jens Nørskov and Ulrik Nielsen.

Since my move to Ames, I have turned my attentions to the study of large scale classical dynamics simulations, using a variation of the corrected effective medium theory. This allows reliable interaction potentials to be calculated with sufficient efficacy to model realistic systems with respect to size, temperature effects and simulation time. This has been used to examine the oxidation dynamics and energetics of Ni from the clean surface up to bulk oxidation. In addition, the growth modes of homo-epitaxy and mixed metal systems has been investigated with particular reference to effects caused by defects.

Current work addresses the problem of epitaxial growth from various surface structures and its dependence on temperature, crystal face and metal used. The aim is to understand the onset of surface roughening in terms of the change in interaction energetics with falling coordination number. In addition, the interplay of impact induced translation and post impact thermal diffusion show direct correlation to the preferred growth mode for a given set of initial conditions.

In addition I am working on two projects to integrate computer technology into the teaching environment of the United States. The first is the Department of Energy sponsored Adventures in Super Computing project which has been running for the past five years. This project has integrated computers into the K-12 curricula of 70 schools in five states. It is unique in its approach in that it provides not only the local computer hardware and network infrastructure, but also the off site connection to the internet and accounts for each student on a DOE super computer. In addition it provides training for the teachers and advises them on the construction of course work. I was responsible for the Iowa hardware and network connection for our fifteen schools, in addition to teacher training and student mentoring.

The second project to which I contribute is the Technical Corps initiated by President Clinton on 10th October 1995. The aim of the project is to connect every classroom in America to the Information Superhighway by the year 2000 and to ensure the technological literacy of every child for the dawn of the 21st century. More information is available at: http://www.techcorps.org.

Since moving to work full time with the Scalable Computing Laboratory, I have been involved in the issues of parallel computing using commodity component compute hardware connected with both commodity Ethernet and dedicated System Area Networks. Both the administrative aspects of cluster configuration and performance analysis of a particular solution, and resource management, have been productive areas of research.