H. Gutfreund - Academia.edu (original) (raw)
Papers by H. Gutfreund
The Formative Years of Relativity, 2017
This chapter concerns the ongoing debate about the meaning of Einstein's theory in the format... more This chapter concerns the ongoing debate about the meaning of Einstein's theory in the formative years, with particular attention to the relation between physics and geometry. It also compares Einstein's thinking on this issue with that of the French mathematician and philosopher Henri Poincaré and deals with the role of symmetry in the theory of relativity—one of Einstein's enduring legacies. The role of symmetry becomes evident, for instance, in the lecture on special relativity, in which it is shown how relativistic invariance, a symmetry property of the spacetime continuum, shapes Maxwell's equations and other laws of physics. In the period under consideration, the understanding of symmetry is deepened by the emergence of Emmy Noether's famous theorems, for which the theory of general relativity was an important source of inspiration.
Frontiers for Young Minds, May 4, 2022
This article describes one of the most important chapters in scientific history, which contribute... more This article describes one of the most important chapters in scientific history, which contributed to the modern understanding of the universe. Albert Einstein completed his theory of general relativity in. This theory changed our understanding of the concepts of space, time and gravity, established by Isaac Newton. One prediction of the new theory was that light rays reaching us from distant stars, curve when they pass near the sun, because of the sun's gravity and the nature of space and time. This prediction was confirmed through astronomical observations measuring the light reaching Earth from distant stars. When this result was published, it ignited a big excitement and interest in the scientific community and the general public, and Einstein became a superstar overnight.
The Formative Years of Relativity
The Road to Relativity, 2015
Physical Review B, 1978
Phonon spectra of organic linear conductors in the Peierls (semiconducting) phase are considered.... more Phonon spectra of organic linear conductors in the Peierls (semiconducting) phase are considered. It is shown that infrared absorption and Raman scattering can give information on the electron-phonon couplings of the various phonons, A rather sharp structure is predicted also above the electronic gap which is due to interference efFects.
Physical Review B, 1974
This paper deals extensively with the coupling of phonons to an electron gas with a Fermi surface... more This paper deals extensively with the coupling of phonons to an electron gas with a Fermi surface consisting of two parallel. planes and its effect on the stability of the lattice and on the phonon dispersion around 2p F. The phonon dispersion and the phonon spectral density distributions are calculated at zero temperature for the equidistant and the deformed lattice, and at temperatures above the transition temperature to the deformed lattice. Two excitation branches are found under certain conditions. The calculation is performed in the random-phase approximation, but the effect of vertex renorrnalization by summing all ladder diagrams is discussed. The phonon dispersion in the distorted lattice is also treated within the framework of the Sawada model.
Advances in Superconductivity, 1983
ABSTRACT
Solid State Communications, 1979
ABSTRACT
The Formative Years of Relativity, 2018
The Journal of Chemical Physics, 1969
ABSTRACT
Solid State Communications, 1987
The Formative Years of Relativity
This chapter shows how Einstein has developed and described the mathematical apparatus that is ne... more This chapter shows how Einstein has developed and described the mathematical apparatus that is necessary to formulate the physical contents of the general theory of gravity. It first discusses the transition from the special to the general relativity principle. According to Einstein's understanding of such a general relativity principle, physical laws are independent of the state of motion of the reference space in which they are described. The chapter argues that such a generalization of the relativity principle to include accelerated reference frames is possible because all inertial effects caused by acceleration can be alternatively attributed to the presence of a gravitational field. The model of a rotating disk is then used to show that general relativity implies non-Euclidean geometry and that the gravitational field is represented by curved spacetime. After the introduction of these basic concepts and principles, the chapter presents the mathematical formulation of the th...
Journal of Physics C: Solid State Physics, 1985
It is shown that a quadratic electron-phonon interaction leads, under certain conditions, to temp... more It is shown that a quadratic electron-phonon interaction leads, under certain conditions, to temperature-dependent band narrowing and an inverse lifetime quadratic in the phonon occupation numbers. These explain the prominent metallic properties of organic metals of the TTF-TCNQ family, in particular the enhancement of the magnetic susceptibility.
Journal of Physics C: Solid State Physics, 1984
Acoustic plasmon excitations have been proposed as a possible mechanism for superconductivity in ... more Acoustic plasmon excitations have been proposed as a possible mechanism for superconductivity in systems with 'heavy' and 'light' electrons. The authors formulate a theory of superconductivity in which electron excitations play the role of phonons in the conventional theory. The main qualitatively new aspect of such a theory is the role of exchange. The effect of exchange on the electron-acoustic-plasmon coupling parameter lambda is estimated.
Elementary Excitations in Solids, Molecules, and Atom, 1974
ABSTRACT The transition to insulating or superconducting states in linear chain systems is discus... more ABSTRACT The transition to insulating or superconducting states in linear chain systems is discussed in relation to the recently observed paraconductivity in TTF-TCNQ crystals. A relation between Tc, the Peierls transition temperature Tp, and the electron-phonon coupling strength is derived using the RPA and a simplified form the strong coupling equation for Tc. It is argued that in principle one can have either Tp>Tc or Tc>Tp.
Solid State Communications, 1979
ABSTRACT
Solid State Communications, 1978
ABSTRACT
Journal de Physique Lettres, 1974
Reçu le 21 mai 1974) Résumé. 2014 Cet article donne la solution des équations d'Eliashberg pour l... more Reçu le 21 mai 1974) Résumé. 2014 Cet article donne la solution des équations d'Eliashberg pour le cas unidimensionnel. Pour chaque valeur de 03C90/EF, il existe une valeur critique de couplage sc au sens suivant : pour s sc, la température critique Tc est plus grande que la température de transition de Peierls Tp tandis que pour s > sc, il n'existe pas de transition BCS.
Solid State Communications, 1980
ABSTRACT An ab-initio calculation of the electron relaxation rates in TTF-TCNQ for one phonon and... more ABSTRACT An ab-initio calculation of the electron relaxation rates in TTF-TCNQ for one phonon and two-phonon processes, resulting from the linear and quadratic electron-phonon coupling is performed. This calculation is based on the detailed molecular structure. It is shown that the relaxation rates due to quadratic coupling processes are at least of the same order of magnitude as the relaxation rate for one-phonon processes. The quadratic coupling processes are dominated by molecular librations, while the linear coupling processes are dominated by translations.
The Formative Years of Relativity, 2017
This chapter concerns the ongoing debate about the meaning of Einstein's theory in the format... more This chapter concerns the ongoing debate about the meaning of Einstein's theory in the formative years, with particular attention to the relation between physics and geometry. It also compares Einstein's thinking on this issue with that of the French mathematician and philosopher Henri Poincaré and deals with the role of symmetry in the theory of relativity—one of Einstein's enduring legacies. The role of symmetry becomes evident, for instance, in the lecture on special relativity, in which it is shown how relativistic invariance, a symmetry property of the spacetime continuum, shapes Maxwell's equations and other laws of physics. In the period under consideration, the understanding of symmetry is deepened by the emergence of Emmy Noether's famous theorems, for which the theory of general relativity was an important source of inspiration.
Frontiers for Young Minds, May 4, 2022
This article describes one of the most important chapters in scientific history, which contribute... more This article describes one of the most important chapters in scientific history, which contributed to the modern understanding of the universe. Albert Einstein completed his theory of general relativity in. This theory changed our understanding of the concepts of space, time and gravity, established by Isaac Newton. One prediction of the new theory was that light rays reaching us from distant stars, curve when they pass near the sun, because of the sun's gravity and the nature of space and time. This prediction was confirmed through astronomical observations measuring the light reaching Earth from distant stars. When this result was published, it ignited a big excitement and interest in the scientific community and the general public, and Einstein became a superstar overnight.
The Formative Years of Relativity
The Road to Relativity, 2015
Physical Review B, 1978
Phonon spectra of organic linear conductors in the Peierls (semiconducting) phase are considered.... more Phonon spectra of organic linear conductors in the Peierls (semiconducting) phase are considered. It is shown that infrared absorption and Raman scattering can give information on the electron-phonon couplings of the various phonons, A rather sharp structure is predicted also above the electronic gap which is due to interference efFects.
Physical Review B, 1974
This paper deals extensively with the coupling of phonons to an electron gas with a Fermi surface... more This paper deals extensively with the coupling of phonons to an electron gas with a Fermi surface consisting of two parallel. planes and its effect on the stability of the lattice and on the phonon dispersion around 2p F. The phonon dispersion and the phonon spectral density distributions are calculated at zero temperature for the equidistant and the deformed lattice, and at temperatures above the transition temperature to the deformed lattice. Two excitation branches are found under certain conditions. The calculation is performed in the random-phase approximation, but the effect of vertex renorrnalization by summing all ladder diagrams is discussed. The phonon dispersion in the distorted lattice is also treated within the framework of the Sawada model.
Advances in Superconductivity, 1983
ABSTRACT
Solid State Communications, 1979
ABSTRACT
The Formative Years of Relativity, 2018
The Journal of Chemical Physics, 1969
ABSTRACT
Solid State Communications, 1987
The Formative Years of Relativity
This chapter shows how Einstein has developed and described the mathematical apparatus that is ne... more This chapter shows how Einstein has developed and described the mathematical apparatus that is necessary to formulate the physical contents of the general theory of gravity. It first discusses the transition from the special to the general relativity principle. According to Einstein's understanding of such a general relativity principle, physical laws are independent of the state of motion of the reference space in which they are described. The chapter argues that such a generalization of the relativity principle to include accelerated reference frames is possible because all inertial effects caused by acceleration can be alternatively attributed to the presence of a gravitational field. The model of a rotating disk is then used to show that general relativity implies non-Euclidean geometry and that the gravitational field is represented by curved spacetime. After the introduction of these basic concepts and principles, the chapter presents the mathematical formulation of the th...
Journal of Physics C: Solid State Physics, 1985
It is shown that a quadratic electron-phonon interaction leads, under certain conditions, to temp... more It is shown that a quadratic electron-phonon interaction leads, under certain conditions, to temperature-dependent band narrowing and an inverse lifetime quadratic in the phonon occupation numbers. These explain the prominent metallic properties of organic metals of the TTF-TCNQ family, in particular the enhancement of the magnetic susceptibility.
Journal of Physics C: Solid State Physics, 1984
Acoustic plasmon excitations have been proposed as a possible mechanism for superconductivity in ... more Acoustic plasmon excitations have been proposed as a possible mechanism for superconductivity in systems with 'heavy' and 'light' electrons. The authors formulate a theory of superconductivity in which electron excitations play the role of phonons in the conventional theory. The main qualitatively new aspect of such a theory is the role of exchange. The effect of exchange on the electron-acoustic-plasmon coupling parameter lambda is estimated.
Elementary Excitations in Solids, Molecules, and Atom, 1974
ABSTRACT The transition to insulating or superconducting states in linear chain systems is discus... more ABSTRACT The transition to insulating or superconducting states in linear chain systems is discussed in relation to the recently observed paraconductivity in TTF-TCNQ crystals. A relation between Tc, the Peierls transition temperature Tp, and the electron-phonon coupling strength is derived using the RPA and a simplified form the strong coupling equation for Tc. It is argued that in principle one can have either Tp>Tc or Tc>Tp.
Solid State Communications, 1979
ABSTRACT
Solid State Communications, 1978
ABSTRACT
Journal de Physique Lettres, 1974
Reçu le 21 mai 1974) Résumé. 2014 Cet article donne la solution des équations d'Eliashberg pour l... more Reçu le 21 mai 1974) Résumé. 2014 Cet article donne la solution des équations d'Eliashberg pour le cas unidimensionnel. Pour chaque valeur de 03C90/EF, il existe une valeur critique de couplage sc au sens suivant : pour s sc, la température critique Tc est plus grande que la température de transition de Peierls Tp tandis que pour s > sc, il n'existe pas de transition BCS.
Solid State Communications, 1980
ABSTRACT An ab-initio calculation of the electron relaxation rates in TTF-TCNQ for one phonon and... more ABSTRACT An ab-initio calculation of the electron relaxation rates in TTF-TCNQ for one phonon and two-phonon processes, resulting from the linear and quadratic electron-phonon coupling is performed. This calculation is based on the detailed molecular structure. It is shown that the relaxation rates due to quadratic coupling processes are at least of the same order of magnitude as the relaxation rate for one-phonon processes. The quadratic coupling processes are dominated by molecular librations, while the linear coupling processes are dominated by translations.