Harold T. Stokes

Education: Employment:


Links to course home pages:

Teaching resources which I and my colleagues have developed for the courses I teach:

Textbooks which I have written for solid state physics courses.

Current research interests

Phase transitions in solids

I have been collaborating with Professor Dorian M. Hatch since 1983 on this project. We have been applying group-theoretical methods to the study of transitions between crystalline phases in solids. One of the major successes of our work has been the establishment of a large data base and the implementation of computer algorithms to carry out the group-theoretical computations in a wide variety of cases. (Click here for information about downloading this software.) Our collaboration has resulted in 28 jointly-authored papers in refereed journals over the last fourteen years . In addition, we published a major reference work, Isotropy Subgroups of the 230 Crystallographic Space Groups, and played a major role in preparing the 1993 English edition of the Russian reference work, Representations of the Crystallographic Space Groups, by O. V. Kovalev.

Most recently, we have been collaborating with Dr. G. M. Chechin and Dr. V. P. Sakhnenko at the Rostov State University in Rostov-on-Don, Russia. They developed a group-theoretical method for treating non-linear oscillations of atoms in crystals. We are implementing some of their ideas on computer.

First-principles calculations in solids

I spent the 1993-94 academic year on professional leave at the Naval Research Laboratory in Washington, D.C. I collaborated with Dr. Larry Boyer in developing computer software for implementing a new type of first-principles energy calculation in crystalline solids. "First principles" means no adjustable parameters. Such calculations are used to determine various properties of materials, such as crystalline structure, elastic constants, vibrational spectra, and phase diagrams, all from first principles with no adjustable parameters. Of course, we have a long way to go before such calculations can produce quick, accurate results. I am continuing the development of these methods here at BYU on a Hewlett Packard workstation (700 series).

Papers and Talks

Papers published in refereed journals


Invited papers at scientific meetings

Contributed papers at scientific meetings