Atomistic Modeling of the Phonon Dispersion and Lattice Properties of Free-Standing H100i Si Nanowires
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INNER ELASTICITY and the HIGHER-ORDER ELASTICITY of Some DIAMOND and GRAPHITE ALLOTROPES
INNER ELASTICITY and the HIGHER-ORDER ELASTICITY of some DIAMOND and GRAPHITE ALLOTROPES Submitted by Christopher Stanley George Cousins to the University of Exeter as a thesis for the degree of Doctor of Philosophy in Physics (March 2001) This thesis is available for Library use on the understanding that it is copy- right material and that no quotation from it may be published without proper acknowledgment. I certify that all material in this thesis which is not my own work has been identi®ed and that no material is included for which a degree has previously been conferred upon me. Abstract Following a brief and selective history of elasticity, the general theory of the rÃole of relative sublattice displacements on the elasticity of single-crystalline material is elaborated in Chapter 1. This involves the de®nition of (a) rotationally-invariant inner displacements and (b) the internal strain tensors that relate those inner displacements to the external strain. The total elastic constants of such materials can then be decomposed into partial and internal parts, the former free of, and the latter involving, the inner displacement(s). Six families of inner elastic constants are needed to characterize the internal parts of the second- and third-order constants. The relation of the second- order inner elastic constants to the longwave coupling constants of lattice dynamics is shown, and a new form of secular equation for the frequencies and eigenvectors of the optic modes at the zone centre is given. In Chapter 2 the point-group symmetry implications for the inner elastic constants are explored in detail. -
Information to Users
INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the back of the book. Photographs included in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 313/761 -4700 800/521-0600 Order Number 0211246 Structural, dynamical and optical properties of the semiconductors Si and Ge and their superlattice Wei, Siqing, Ph.D. The Ohio State University, 1991 Copyright ©1991 by Wei, Siqing. -
Atomic Structure of Dislocation Kinks in Silicon
PHYSICAL REVIEW B VOLUME 57, NUMBER 17 1 MAY 1998-I Atomic structure of dislocation kinks in silicon R. W. Nunes Complex System Theory Branch, Naval Research Laboratory, Washington, DC 20375-53459 and Computational Sciences and Informatics, George Mason University, Fairfax, Virginia 22030 J. Bennetto and David Vanderbilt Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08855-0849 ~Received 16 July 1997; revised manuscript received 15 October 1997! We investigate the physics of the core reconstruction and associated structural excitations ~reconstruction defects and kinks! of dislocations in silicon, using a linear-scaling density-matrix technique. The two predomi- nant dislocations ~the 90° and 30° partials! are examined, focusing for the 90° case on the single-period core reconstruction. In both cases, we observe strongly reconstructed bonds at the dislocation cores, as suggested in previous studies. As a consequence, relatively low formation energies and high migration barriers are generally associated with reconstructed ~dangling-bond-free! kinks. Complexes formed of a kink plus a reconstruction defect are found to be strongly bound in the 30° partial, while the opposite is true in the case of 90° partial, where such complexes are found to be only marginally stable at zero temperature with very low dissociation barriers. For the 30° partial, our calculated formation energies and migration barriers of kinks are seen to compare favorably with experiment. Our results for the kink energies on the 90° partial are consistent with a recently proposed alternative double-period structure for the core of this dislocation. @S0163-1829~98!10617-3# I. INTRODUCTION and the high Peierls potential barrier to kink motion control the rate of dislocation propagation. -
Theoretical Study of the Structure, Energetics, and Dynamics of Silicon and Carbon Systems Using Tight-Binding Approaches " (1991)
Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1991 Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight- binding approaches Chunhui Xu Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Condensed Matter Physics Commons Recommended Citation Xu, Chunhui, "Theoretical study of the structure, energetics, and dynamics of silicon and carbon systems using tight-binding approaches " (1991). Retrospective Theses and Dissertations. 9789. https://lib.dr.iastate.edu/rtd/9789 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be &om any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. -
The Ge(001) (2 × 1) Reconstruction: Asymmetric Dimers and Multilayer
.,.Y>.. i....... :.:.:.: . :.:.:.:.> .. .:.:.:.:,~ . d:.:.:.:......‘.‘.:.:.:.:......:.:.:.:. .. .. .:,~ . .. .. .. .. .. ..(.:.:.,.,.,.,.,:,,;,., .‘.Y.X . .. .. .. :.:.:.:.::.:.:.:.:.:.:.,.......,........: ,....,.,....:.:, ~ ,....,,:.:.:.~ ,,:, “‘::::.:.::::l:~~~:i:.~... ,’ ‘. .i.....,.. :.:.::: :::: i:~_:~: $y:::... Surface Science 279 (1992) 199-209 surface science North-Holland ... ., .“.’.. ..:. ~.“” .,, “.,.,‘,.~,.~:.:.::::.:.::::::::::::::::~:~~::~:~,:~~~~~~~:~.~.. ,, ,~:.:.:::~~.~~~~,~.~~ ‘:““‘-.-““‘.~:‘...:.:.:..:.:.:“~‘~“::::~::::::::.::::::,,:::::.:~:~:~:~.~:.~.:..‘.‘. (.‘i.Z.. .../._.. .......nj,.,. ,,.,., ,,.,.,_._:;,:~ ;.,,,..(,.,., ..,_ ;;, _,(,, The Ge( 001) (2 x 1) reconstruction: asymmetric dimers and multilayer relaxation observed by grazing incidence X-ray diffraction R. Rossmann, H.L. Meyerheim, V. Jahns, J. Wever, W. Moritz, D. Wolf, D. Dornisch and H. Schulz Institut fiir Kristallographie und Minerabgie der Uniuersitiit Miinchen, Theresienstrasse 41, D-8000 Miinchen 2, Germany Received 25 June 1992; accepted for publication 25 August 1992 Grazing incidence X-ray diffraction has been used to analyze in detail the atomic structure of the (2 X 1) reconstruction of the Ge(OO1) surface involving far reaching subsurface relaxations. Two kinds of disorder models, a statistical and a dynamical were taken into account for the data analysis, both indicating substantial disorder along the surface normal. This can only be correlated to asymmetric dimers. Considering a statistical disorder model assuming randomly oriented dimers -
A Topological Explanation of the Urbach Tail a Thesis Presented To
A Topological Explanation of the Urbach Tail A thesis presented to the faculty of the College of Arts and Sciences of Ohio University In partial fulfillment of the requirements for the degree Master of Science Dale J. Igram April 2016 © 2016 Dale J. Igram. All Rights Reserved 2 This thesis titled A Topological Explanation of the Urbach Tail by DALE J. IGRAM has been approved for the Department of Physics and Astronomy and the College of Arts and Sciences by David A. Drabold Distinguished Professor of Physics and Astronomy Robert Frank Dean, College of Arts and Sciences 3 ABSTRACT IGRAM, DALE J., M.S., April 2016, Physics A Topological Explanation of the Urbach Tail Director of Thesis: David A. Drabold The Urbach tail is considered as one of the most significant properties of amorphous structures because of its almost universal characteristics. Several theoretical attempts have been used to explain the existence of the Urbach tail only to fail. Utilizing the best models, it has been shown that Urbach tails are associated with topological filaments [11]. The original work in this thesis is presented in two parts. The first part involves the effects of thermal statistics on eigenvalues and electronic density of states (EDOS) for a 512 atom a-Si model, which revealed a significant variation of the EDOS and energy gap as a function of temperature; thus, showing how a semiconducting state can change to a conducting state. The second part deals with the comparison of two 4096 atom a-Si models (unrelaxed and relaxed), in which physical and electronic structures were compared, revealing that the connectivity of the short and long bonds for both models indicated that short bonds prefer short bonds and similarly for long bonds, and that short bonds of the relaxed model germinated and proliferated faster as compared to the unrelaxed model. -
Mechanical and Optical Response of Diamond Crystals
MECHANICAL AND OPTICAL RESPONSE OF DIAMOND CRYSTALS SHOCK COMPRESSED ALONG DIFFERENT ORIENTATIONS By JOHN MICHAEL LANG, JR. A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY WASHINGTON STATE UNIVERSITY Department of Physics DECEMBER 2013 © Copyright by JOHN MICHAEL LANG, JR., 2013 All Rights Reserved © Copyright by JOHN MICHAEL LANG, JR., 2013 All Rights Reserved To the Faculty of Washington State University: The members of the Committee appointed to examine the dissertation of JOHN MICHAEL LANG, JR. find it satisfactory and recommend that it be accepted. ___________________________________ Yogendra M. Gupta, Ph.D., Chair ___________________________________ Matthew D. McCluskey, Ph.D. ___________________________________ Philip L. Marston, Ph.D. ii ACKNOWLEDGMENTS I would first like to thank my advisor, Dr. Yogendra Gupta, for providing me with this research opportunity and supporting my work. His guidance and leadership was invaluable to my education and training as a scientist. I am very grateful for his time and effort. I would also like to thank Dr. Matt McCluskey and Dr. Philip Marston for their advice and guidance, and for serving on my committee. I would like to thank the administrative and technical staff of the Institute for Shock Physics for their support of my work. Special thanks to Kurt Zimmerman and Yoshi Toyoda for their assistance with the experimental instrumentation, to Nate Arganbright for his help with materials preparation, to Steve Barner for machining many of the parts used in this work, and to Kent Perkins, Cory Bakeman, and Luke Jones for operating the guns. A warm thank you to Sabreen Dodson and the administrative staff of the Physics Department for their help in guiding me through the policies and requirements of the Graduate School.