Michael P. Teter

Car–Parrinello methods

Brief descriptions are given of the total-energy pseudopotential technique and of Car and Parrinellos molecular dynamics method for performing pseudopotential calculations. A review of the technical problems associated with performing total-energy pseudopotential calculations is presented. A number of alternative computational schemes for performing total-energy pseudopotential calculations are described and it is shown that all the technical problems associated with the total-energy pseudopotential method can be overcome by using a computational scheme based on conjugate gradient techniques.

Density functional methods as computational tools in materials design

SummaryThis article gives a brief overview of density functional theory and discusses two specific implementations: a numerical localized basis approach (DMol) and the pseudopotential plane-wave method. Characteristic examples include Cu, clusters, CO and NO dissociation on copper surfaces, Li-, K-, and O-endohedral fullerenes, tris-quaternary ammonium cations as zeolite template, and oxygen defects in bulk SiO2. The calculations reveal the energetically favorable structures (estimated to be within ± 0.02 Å of experiment), the energetics of geometric changes, and the electronic structures underlying the bonding mechanisms. A characteristic DMo1 calculation on a 128-node nCUBE 2 parallel computer shows a speedup of about 107 over a single processor. A plane-wave calculation on a unit cell with 64 silicon atoms using 1024 nCUBE 2 processors runs about five times faster than on a single-processor CRAY YMP.

Density Functional Methods and Applications to Materials Problems

Density functional theory provides a first-principles approach for computing the geometric and electronic structures, and a wealth of corresponding properties, of a wide range of materials types and compositions, including bulk solids, surfaces, defects and clusters of molecules. Parallel advances in hardware performance, implementation strategies and algorithms have all contributed to a rapid growth in the number of important applications. Recent developments under each of these themes are outlined and the breadth of current applications is illustrated by typical examples. Issues associated with the implementation and performance of density functional methods on parallel computer architectures are discussed.

The Oxygen Vacancy and The E 1 ′ Center In SiO 2

We report parameter-free self-consistent calculations of structural properties for the oxygen vacancy in silicon-dioxide using new oxygen pseudopotentials and quantum molecular dynamics simulations. Results challenge the accepted identification of the oxygen vacancy with the paramagnetic E 1 ′ center. Bonding of the adjacent silicon atoms occurs sufficiently strongly for all charge states to inhibit the asymmetric distortion which would be required for correspondence with the E 1 ′ center.