Download or read book First Principles Study of the Electron phonon Interaction in Metals written by and published by . This book was released on 2010 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A First Principles Investigation of the Electron phonon Interaction in Metals written by and published by . This book was released on 2010 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Electron Phonon Interaction from First Principles written by Jesse Dean Noffsinger and published by . This book was released on 2011 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis the ground state electronic properties, lattice dynamics, electron-phonon coupling and superconductivity of a variety materials are investigated from first principles. The first chapter provides an introduction to the material and concepts of this thesis as well as motivation for the work done herein. Additionally, an overview is given on the theoretical background governing the calculations of this work. This includes overviews of the topics of density functional theory, the pseudopotential approximation, density functional perturbation theory, and applications of these approaches to the calculations of superconductivity. In the second chapter the mechanics of actually performing calculations within the methodology of chapter one are explained. This is accomplished through a detailed description of the computer software EPW. This software has been developed to allow computationally efficient approaches for calculating the electron-phonon interaction. A description of the software package, the particular quantities which it calculates and example calculations are given. The following two chapters present the results of calculations regarding electron-phonon coupling and superconductivity in bulk carbon compounds. The occurrence or absence of superconductivity is found to be related in these compounds to Fermi surface nesting and carrier concentrations. In chapter five we investigate the role of the fluorine dopant in the recently discovered (1111) Fe-pnictide superconductors. Contrary to the results of the literature published shortly after the discovery of these compounds, the presence of the dopant is found to actually result in a net decrease in the electron concentration on the Fe-plane within the local density approximation to density functional theory. In the two chapters which follow, we investigate the limits of two dimensional superconductivity in the recent experiments on ultra-thin Pb samples. Chapter six details calculations on freestanding Pb slabs constructed as thin as two monolayers. A useful formula predicting the electron-coupling strength and therefore estimating the superconducting transition temperature is developed. While in the next section a superconducting system is investigated wherein the important Pb-Si(111) interaction in ultra-thin Pb layers is taken into account. The observed superconductivity is explained by electron-phonon coupling and isotropic Migdal-Eliashberg theory. The observance of superconductivity in the nearly two-dimensional material is shown not to conflict with the predictions of the Mermin-Wagner theorem. In the final chapter, the phonon-assisted absorption of bulk silicon is calculated from first-principles. The calculated results are found to be in excellent agreement with experiment, and lead the way for the possibility of many first-principle studies on phonon-assisted optical processes in important technological devices.

Download or read book First Principles Studies of Phonons and Electrons in Bulk Thermoelectrics written by Yi Xia and published by . This book was released on 2016 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thermoelectric materials, which enable direct conversion between thermal and electrical energy, provide an alternative for power generation and refrigeration. The key parameter that defines the efficiency of thermoelectric materials is the 'dimensionless figure of merit' ZT, which is composed of the Seebeck coefficient, electrical conductivity and total thermal conductivity respectively. Ideally, to achieve high ZT both the Seebeck coefficient and electrical conductivity should be large, while total thermal conductivity must be minimized. In this thesis, first-principles calculations of the Seebeck coefficient, lattice thermal conductivity and electrical conductivity are performed to study mechanisms and factors that gives rise to high ZT. One effective way to enhance ZT is through direct reduction of lattice thermal conductivity. We perform calculation and analysis of lattice thermal conductivity for thermoelectric materials by solving the Boltzmann transport equation iteratively in the framework of perturbation theory. The second- and third-order interatomic force constants are extracted using the recently developed CSLD (compressive sensing lattice dynamics) method. Afterwards, we evaluate opportunities to achieve further reduction of lattice thermal conductivity. Our first study of ternary zinc-blende-based mineral compounds famatinite (Cu3SbS4) and permingeatite (Cu3SbSe4) shows that optical modes in these two compounds contribute a sizable portion of the total lattice thermal conductivity and thus cannot be neglected. Due to the fact that phonon modes with mean free paths larger than 10 nm carry about 80% of the heat, nanostructuring, which reduces the mean free path, is a promising way to reduce the lattice thermal conductivity by reducing the characteristic length. In addition, our simple alloying model including mass disorder reproduces experimental findings that forming solid solutions rapidly decreases the lattice thermal conductivity. An alternative way to reduce lattice thermal conductivity is to introduce guest atoms in host cage structures. Our study of type-I Si clathrates containing guest atoms Na and Ba shows that Na tends to form incoherent localized phonon mode while Ba coherently couples with the host cages. The low lattice thermal conductivities of Na- and Ba-filled Si clathrates should be attributed to the dramatic reductions in both phonon lifetime and group velocity. Analysis of phonon scattering process reveals that localized modes can be effectively emitted and absorbed, thus dramatically enhancing overall scattering rates. Another widely adopted approach to achieve high ZT is through maintaining a high power factor. To accurately determine the Seebeck coefficient and electrical conductivity, we estimate carrier lifetime due to electron-phonon interaction under relaxation time approximation using the electron-phonon Wannier interpolation technique. Our study of noble metals Cu and Ag shows that their positive Seebeck coefficients can be mostly attributed to the negative energy dependence of carrier lifetime. In contrast to the previous study of positive Seebeck in Li, which is due to the deviation of electronic behavior from that in free electron model, it is the nontrivial energy dependence of electron-phonon interaction vertex that leads to the positive Seebeck coefficient. Intermetallic compound B20-type CoSi has drawn considerable attention due to its exceptionally high power factor and large Seebeck coefficient. Our study shows that the large negative Seebeck coefficient of the pristine CoSi is mostly due to the strong energy dependence of carrier lifetime, which together with the high electrical conductivity leads to the high power factor. For heat transport, both electron-phonon and phonon-phonon interactions contribute significantly to phonon scattering at temperatures lower than 200 K. While at temperatures higher than 300 K, phonon-phonon interaction dominates over electron-phonon interaction. Based on the optimized power factor with properly adjusted carrier concentration, we predict that the maximum ZTs at 300 and 600 K are about 0.11 and 0.25 respectively without further reducing the total thermal conductivity. Known good thermoelectric materials often are comprised of elements that are in low abundance, toxic and require careful doping and complex synthesis procedures. High performance thermoelectricity has been reported in earth-abundant compounds based on natural mineral tetrahedrite (Cu12Sb4S13). Our first-principles electronic structure calculations of Cu12Sb4S13 show that Cu atoms are all in the monovalent state, creating two free hole states per formula unit of the pristine compound. Optimal thermoelectric performance can be achieved via electron doping. Substituting transition metals on Cu 12d sites does the job. Detailed analysis shows that Zn and Fe substitutions tend to fill the empty hole states, while Ni substitution introduces an additional hole to the valence band by forming ferromagnetic configuration. Experimentally observed extremely low lattice thermal conductivity can be attributed to the out-of-plane vibrations of the three-fold Cu ions. This is further verified by the large Gruneisen parameter calculated.

Download or read book Electron Phonon Interactions and Phase Transitions written by T. Riste and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: This NATO Advanced Study Institute was the fourth in a series devoted to the subject of phase transitions and instabilities with particular attention to structural phase transforma~ions. Beginning wi th the first Geilo institute in 19'(1 we have seen the emphasis evolve from the simple quasiharmonic soft mode description within the Landau theory, through the unexpected spectral structure re presented by the "central peak" (1973), to such subjects as melting, turbulence and hydrodynamic instabilities (1975). Sophisticated theoretical techniques such as scaling laws and renormalization group theory developed over the same period have brought to this wide range of subjects a pleasing unity. These institutes have been instrumental in placing structural transformations clearly in the mainstream of statistical physics and critical phenomena. The present Geilo institute retains some of the counter cul tural flavour of the first one by insisting whenever possible upon peeking under the skirts of even the most successful phenomenology to catch a glimpse of the underlying microscopic processes. Of course the soft mode remains a useful concept, but the major em phasis of this institute is the microscopic cause of the mode softening. The discussions given here illustrate that for certain important classes of solids the cause lies in the electron phonon interaction. Three major types of structural transitions are considered. In the case of metals and semimetals, the electron phonon interaction relie6 heavily on the topology of the Fermi surface.

Download or read book Materials Modelling Using Density Functional Theory written by Feliciano Giustino and published by Oxford University Press, USA. This book was released on 2014 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book explains the fundamental ideas of density functional theory, and how this theory can be used as a powerful method for explaining and even predicting the properties of materials with stunning accuracy.

Download or read book Notes on the electron phonon interaction written by Сергей Рябчун and published by Litres. This book was released on 2018-09-21 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: These notes are a result of a series of lectures given to the MS and PhD students of the Department of Physics, Moscow State Pedagogical University. They deal with the subject of electron-phonon interaction in pure threedimensional metals. The goal was to show how one could calculate the temperature dependence of the electron-phonon-interaction time from first principles within a simple model. Students wishing to expand their knowledge of the subject of condensed matter are invited to study any book on solid-state physics (for example by J.M. Ziman, or N.W. Ashcroft and N.D. Mermin.

Download or read book The Electron phonon Interaction in Metals written by Göran Grimvall and published by North Holland. This book was released on 1981 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Influence of the Electron phonon Interaction Onto Electronic Transport in Metals written by Florian Rittweger and published by . This book was released on 2018* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron-phonon interaction; density functional theory; first-principles; Boltzmann transport theory; electrical conductivity; thermopower; metals

Download or read book Introduction to the Electron Theory of Metals written by Uichiro Mizutani and published by Cambridge University Press. This book was released on 2001-06-14 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron theory of metals textbook for advanced undergraduate students of condensed-matter physics and related disciplines.

Download or read book Springer Handbook of Surface Science written by Mario Rocca and published by Springer Nature. This book was released on 2021-01-14 with total page 1273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook delivers an up-to-date, comprehensive and authoritative coverage of the broad field of surface science, encompassing a range of important materials such metals, semiconductors, insulators, ultrathin films and supported nanoobjects. Over 100 experts from all branches of experiment and theory review in 39 chapters all major aspects of solid-state surfaces, from basic principles to applications, including the latest, ground-breaking research results. Beginning with the fundamental background of kinetics and thermodynamics at surfaces, the handbook leads the reader through the basics of crystallographic structures and electronic properties, to the advanced topics at the forefront of current research. These include but are not limited to novel applications in nanoelectronics, nanomechanical devices, plasmonics, carbon films, catalysis, and biology. The handbook is an ideal reference guide and instructional aid for a wide range of physicists, chemists, materials scientists and engineers active throughout academic and industrial research.

Download or read book Principles of Electron Tunneling Spectroscopy written by E. L. Wolf and published by Oxford University Press. This book was released on 2012 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

Download or read book First principles Studies of Carbon Nanostructures and Spin phonon and Electron phonon Coupling in Solids written by Kevin Timothy Chan and published by . This book was released on 2012 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents first-principles theoretical studies on two topics of condensed matter physics. The first topic is the adsorption of metal adatoms on graphene. Graphene, a two-dimensional material made of carbon atoms arranged in a honeycomb lattice, has many outstanding properties that can be enhanced or tailored by adsorbing adatoms on its surface. The second topic involves the coupling of spins or electrons to phonons in a solid. The interaction between different degrees of freedom of a material complicates the study of its properties but also leads to fascinating phenomena, such as superconductivity, and potential device applications. This dissertation is organized into six chapters: · In Chapter One, we give an overview of this work and review the first-principles theory and methods used in our studies. · Chapter Two focuses on structural, energetic, and electronic properties for a variety of adatom species adsorbed on the graphene surface. We classify different species as having mostly ionic or covalent character of bonding to graphene. For ionically bonded adatoms, charge transfer between the adatom and graphene is signficant. We find general trends relating the surface dipole moment, work function, and atomic ionization potential of the adatom species. · In Chapter Three, we study the electronic structure of adatoms on graphene when a gate voltage is applied to control the number of electrons in the system. Lithium on graphene, a prototype system, and cobalt on graphene, an experimentally relevant case, are studied. We find that localized states on the adatom can be charged or discharged by the application of gate voltage, and we study the changes in potential and charge density of the system as electrons are added or removed. · In Chapter Four, we extend the work in Chapter Three to consider the possibility of transforming the electronic structure of one species of adatom on graphene into that of another by applying a gate voltage. We find that within our model, such transformations are possible for certain adatom species. · In Chapter Five, the zone-center phonons for the frustrated antiferromagnetic compound ZnCr2O4 are calculated. We find that the transition from nonmagnetic to antiferromagnetic ordering causes a splitting of certain degnerate phonon frequencies, in agreement with experimental results. · In Chapter Six, the pressure dependence of electron-phonon coupling and the superconducting transition temperature (Tc) in elemental arsenic is studied. We find that an experimentally observed peak in Tc as a function of pressure is related to a structural transition and can be explained mainly by changes in electronic structure and phonon frequencies with pressure.

Download or read book Conceptual Foundations of Materials written by and published by Elsevier. This book was released on 2006-09-20 with total page 245 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this Volume "Conceptual Foundations of Materials: A standard model for ground- and excited-state properties" is to present the fundamentals of electronic structure theory that are central to the understanding and prediction of materials phenomena and properties. The emphasis is on foundations and concepts. The Sections are designed to offer a broad and comprehensive perspective of the field. They cover the basic aspects of modern electronic structure approaches and highlight their applications to the structural (ground state, vibrational, dynamic and thermodynamic, etc.) and electronic (spectroscopic, dielectric, magnetic, transport, etc.) properties of real materials including solids, clusters, liquids, and nanostructure materials. This framework also forms a basis for studies of emergent properties arising from low-energy electron correlations and interactions such as the quantum Hall effects, superconductivity, and other cooperative phenomena. Although some of the basics and models for solids were developed in the early part of the last century by figures such as Bloch, Pauli, Fermi, and Slater, the field of electronic structure theory went through a phenomenal growth during the past two decades, leading to new concepts, understandings, and predictive capabilities for determining the ground- and excited-state properties of real, complex materials from first principles. For example, theory can now be used to predict the existence and properties of materials not previously realized in nature or in the laboratory. Computer experiments can be performed to examine the behavior of individual atoms in a particular process, to analyze the importance of different mechanisms, or just to see what happen if one varies the interactions and parameters in the simulation. Also, with ab initio calculations, one can determine from first principles important interaction parameters which are needed in model studies of complex processes or highly correlated systems. Each time a new material or a novel form of a material is discovered, electronic structure theory inevitably plays a fundamental role in unraveling its properties. Provides the foundations of the field of condensed matter physics An excellent supplementary text for classes on condensed matter physics/solid state physics Volume covers current work at the forefront Presentations are accessible to nonspecialists, with focus on underlying fundamentals

Download or read book Electron Phonon Interactions written by Albert Rose and published by World Scientific. This book was released on 1989 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph is a radical departure from the conventional quantum mechanical approach to electron-phonon interactions. It translates the customary quantum mechanical analysis of the electron-phonon interactions carried out in Fourier space into a predominantly classical analysis carried out in real space. Various electron-phonon interactions such as the polar and nonpolar optical phonons, acoustic phonons that interact via deformation potential and via the piezoelectric effect and phonons in metals, are treated in this monograph by a single, relatively simple ?classical? model. This model is shown to apply to electron interactions with the deep lying X-ray levels of atoms, with plasmons and with Cerenkov radiation. The unifying concept that applies to all of these phenomena is a new definition of a coupling constant. The essentially classical interaction of an electron with its surrounding is clearly brought out to be the cause of spontaneous emission of phonons. The same concept also applies to the case of spontaneous emission of photons. While the bulk of this monograph deals with quanta of phonons and quanta of photons, a discussion of the acousto electric effect which is a purely classical phenomenon is presented. The newly defined coupling constant turns out to be valid too for this discussion. This universality of the coupling constant goes far beyond. It is equally applicable to amorphous materials. This significant application gives an analytic formulation of mobility in amorphous materials.

Download or read book A Field Theoretic Study of Electron Phonon Interactions in Metals written by Sami Hakim Mikhail and published by . This book was released on 1974 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electron phonon Interactions in Low dimensional Structures written by Lawrence John Challis and published by . This book was released on 2003 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of electrons and holes confined to two, one and even zero dimensions has uncovered a rich variety of new physics and applications. This book describes the interaction between these confined carriers and the optic and acoustic phonons within and around the confined regions. Phonons provide the principal channel of energy transfer between the carriers and their surroundings and also the main restriction to their room temperature mobility. But they have many other roles; they provide, for example, an essential feature of the operation of the quantum cascade laser. Since their momenta at relevant energies are well matched to those of electrons, they can also be used to probe electronic properties such as the confinement width of 2D electron gases and the dispersion curve of quasiparticles in the fractional quantum Hall effect. The book describes both the physics of the electron-phonon interaction in the different confined systems and the experimental and theoretical techniques that have been used in its investigation. The experimental methods include optical and transport techniques as well as techniques in which phonons are used as the experimental probe. The aim of the book is to provide an up to date review of the physics and its significance in device performance. It is also written to be explanatory and accessible to graduate students and others new to the field.