Epitaxial Bain paths and metastable phases from first-principles total-energy calculations

2002 ◽  
Vol 66 (6) ◽  
Author(s):  
P. M. Marcus ◽  
F. Jona ◽  
S. L. Qiu
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Metastable Phases ◽  
Energy Calculations ◽  
Epitaxial Bain Paths

Migration of Aluminum Atoms in the Transformation of γ–to θ–Alumina

2002 ◽  
Vol 731 ◽  
Author(s):  
Shu-Hui Cai ◽  
Karl Sohlberg
Keyword(s):  
Aluminum Oxide ◽  
Total Energy ◽  
First Principles ◽  
Conversion Rate ◽  
Metastable Phases ◽  
Thermal Dehydration ◽  
First Principles Calculations ◽  
Energy Calculations ◽  
Domain Boundaries ◽  
Transformation Pathways

Abstractγ– and θ–alumina are two metastable phases of aluminum oxide observed along the thermal dehydration sequence of boehmite before conversion to the final product α–alumina. The transformation from γ– to θ–alumina was studied by using Al16O24 cells. Motion of some Al atoms from their γalumina positions to new positions and no O motions result in an approximate structure that, upon relaxation by first-principles calculations, becomes the known θ–alumina structure. Total-energy calculations along the paths of the atomic motions have been used to map out transformation pathways. The model accurately predicts experimentally observed domain boundaries in θ–alumina and the γ– to θ–alumina conversion rate.

Phase Stability of the Sigma Phase in Fe-Cr Based Alloys

1995 ◽  
Vol 408 ◽  
Author(s):  
Marcel Il. F ◽  
Sluiter. Koivan Esfurjani ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Total Energy ◽  
Phase Stability ◽  
First Principles ◽  
Finite Temperature ◽  
Sigma Phase ◽  
Complex Structure ◽  
Unit Cell ◽  
Energy Calculations ◽  
Cluster Variation ◽  
The Stability

AbstractThe FeCr sigma phase is a good example of a complex structure: it. has 30 atoms in the unit cell and 5 inequivalent lattice sites, and it belongs to the class of tetrahedrally close packed structures, also known as Frank-Kaspar structures. So far. such structures have riot been treated within a first-principles statistical thermodynamics framework. It will be shown that dtlme to advances in algorithms and hardware important features of the phase stability of complex phases can be computed. The factors which affect the stability of the sigma phase have been studied using carefully selected supercells for electronic total energy calculations. cluster variation calc:ulations in the tet.rahedron approximation were performed to evaluate the effect of partial disorder and of finite temperature. The preferred occupancy of the 5 lattice sites has been investigated and is compared with experimental determinations.

Real-space implementation of nonlocal pseudopotentials for first-principles total-energy calculations

1991 ◽  
Vol 44 (23) ◽  
pp. 13063-13066 ◽  
Author(s):  
R. D. King-Smith ◽  
M. C. Payne ◽  
J. S. Lin
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Real Space ◽  
Energy Calculations

A Theoretical Study of p-Type Doping of ZnO: Problems and Solutions

2001 ◽  
Vol 666 ◽  
Author(s):  
Yanfa Yan ◽  
S.B. Zhang ◽  
S.J. Pennycook ◽  
S.T. Pantelides
Keyword(s):  
Total Energy ◽  
First Principles ◽  
Theoretical Study ◽  
Energy Calculations ◽  
Defect Complexes ◽  
New Approaches ◽  
Impurity Defect ◽  
Problems And Solutions ◽  
P Type ◽  
Made In

ABSTRACTWe present results of a comprehensive set of first-principles total-energy calculations of native and impurity-defect complexes in ZnO and use these results to elucidate the problems that occur in efforts to achieve p-type doping. The analysis naturally leads to new approaches that are likely to overcome the difficulties. The results provide detailed explanations of recent puzzling observations made in attempts to produce p-type ZnO.

scholarly journals Theory of Hydrogen Reactions in Silicon

1987 ◽  
Vol 104 ◽  
Author(s):  
Chris G. Van De Walle ◽  
Y. Bar-Yam ◽  
S. T. Pantelides
Keyword(s):  
Fermi Level ◽  
Total Energy ◽  
First Principles ◽  
Type Material ◽  
Energy Calculations ◽  
And Migration ◽  
The Stability ◽  
Hydrogen Reactions ◽  
Energy Surfaces ◽  
P Type

ABSTRACTWe report first-principles total-energy calculations for H atoms in a Si lattice. Our results for single H atoms are presented in the form of total-energy surfaces, providing immediate insight in stable positions and migration paths. We examine the stability of different charge states (H+, H0, H−) as a function of Fermi-level position, and its impli-cations for H diffusion in p-type vs. n-type material. The results are used to scrutinize and supplement existing understanding of experimental observations. We also study the co-operative interactions of several H atoms, and propose a novel mechanism for H-induced damage.

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