Karin M. Rabe

Address

Department of Applied Physics, Yale University, P.O. Box 208284, New Haven, CT 06520

Phone: (203) 432 - 1816 ; Fax: (203) 432 - 4283

E-mail: rabe@critical.eng.yale.edu

Office: 309 Becton

Research Interests

Karin Rabe uses a variety of techniques to attack one of the most fundamental problems in condensed matter physics: the derivation of simple models for crystal structure and hence the physical properties of real materials from the underlying quantum-mechanical system of interacting nuclei and electrons. Due to a number of theoretical advances in density functional theory and the pseudopotential approach, it is now possible with the aid of high-speed computers to perform first-principles total-energy calculations in which the ground state energy for a particular crystal configuration is obtained by numerically solving the Schrodinger equation. With the only input being the atomic numbers of the constituent elements, zero temperature properties including crystal structure, elastic constants, phonon frequencies, surface reconstructions, and atomic relaxations at defects can be accurately predicted. The extension of first-principles techniques to finite temperature phenomena, particularly phase transitions, has been and continues to be one of the major components of Rabe's research. Most recently she has focused on fascinating and technologically-important ferroelectric materials such as PbTiO3 and PbZrO3, and has made significant progress towards a first-principles predictive theory of ferroelectric phase transition.

Powerful and accurate as these first-principles methods are, their applicability remains limited to relatively simple systems. However, some of the most interesting physics related to structural instabilities, e.g. stable quasicrystallinity and high-temperature ferroelectrics and superconductors, occurs primarily in crystals with very complex structures. To study these phenomena, Rabe is involved in a collaboration with J.C. Phillips of AT&T Bell Laboratories and P. Villars of the Intermetallic Phases Databank in Switzerland to explore a complementary technique involving the diagram-based statistical analysis of measured properties of the full database of known compounds. With such an analysis, special groups of compounds (e.g., stable quasicrystals) can easily be put into context and the chemical factors favoring the occurrence of the special property identified. The results lead not only to a better understanding of the physics of these compounds, but also provide practical strategies for the prediction of new materials of direct assistance to experimentalists in this area.

References

"Optimized Pseudopotentials'', A.M. Rappe, K.M. Rabe, E. Kaxiras and J.D. Joannopoulos, Phys. Rev. B 41, 1227 (1990).

"Global Multinary Structural Chemistry of Stable Quasicrystals, High Tc Ferroelectrics and Superconductors'', K.M. Rabe, J.C. Phillips, P. Villars, and I.D. Brown, Phys. Rev. B 45, 7650 (1992).

"First-Principles Model Hamiltonians for Ferroelectric Phase Transitions'' K.M. Rabe and U.V. Waghmare, Ferroelectrics, 136, 147 (1992).

"Ab Initio pseudopotential calculations of aluminum-rich cobalt compounds'', S. Ogut and K.M. Rabe, Phys. Rev. B 50, (1994), in press.

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