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Phenomenological theory of the interaction of electrons with polar phonons in anisotropic crystals
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11.
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
PHENOMEONOLOGICAL THEORY OF THE INTERACTION OF ELECTRONS WITH POLAR PHONONS IN ANISOTROPIC
13.
CRYSTALS E. Bergmann, Battelle Institute, Advanced Studies Center, CH-1227 Carouge-Geneva, Switzerland. The generalized phenomenological lattice equations of Huang are used to derive the Hamiltonian of the coupled electron phonon system in an anisotropic crystal. The dependence of the coupling constant on the angle formed by the phonon wave vector and the axis of an uniaxial crystal is given explicitly. A significant dependence of the coupling constant on this angle persists even in the case of dominant mechanical or electrostatic forces. Received 21 January 1974 Revised 12Apr11 1974
12.
THE ELECTRONIC CHARGE DENSITIES IN SEMICONDUCTING LAYER AND CHAIN STRUCTURES E. Mooser, I.Ch. SchlUter and M. Schlüter, Laboratoire de Physique Appliquée, Ecole Polytechnique Fédérale, Lausanne, Switzerland.
DIPOLAR INTERACTIONS IN RARE EARTH ORTHOFERRITES PART I: YFeO3 AND HoFeO3 R. Bidaux, J.E. Bouree and J. Hammann, Service de Physique du Solide et de Resonance Magnétique, Centre d’Etudes Nucléaires de Saclay, BP no 2 —91, Gif-sur-Yvette, France.
The part of dipolar interactions in the magnetic properties of YFeO3 and HoFeO3 is examined in detail. In YFeO3, one finds that the contribution of these interactions to the anisotropy in the xOz plane (easy magnetization plane for the iron moments) has the same order of magnitude as the crystalline anisotropy. In the case of HoFeO3, the molecular field formalism is used in order to interpret the existence of a single, ferromagnetic ordered structure for temperatures below a rearrangement temperature TR. The physical parameters introduced within the framework of this formalism are fitted by comparison with the available experimental results. Received 10 January 1974 Revised 18 March 1974 14.
From calculations of the pseudo-wavefunctions the charge densities of the valence electrons in the semiconducting crystals SnSe2, Pb12, GaSe, Se and Te have been determined. The results are compared with the valence bond description of semiconductors which can thus be confirmed and refined. Insight is gained into the accommodation in the valence bands of the excess s-electrons in PbI2 and GaSe. For Te the transformation from the trigonal to the simple cubic modification has been simulated on the computer. The changes of the charge densities occuring in this semiconductor-to-metal transition are discussed. Received 13 December 1973
Vol. 15, No.2
DETERMINATION DE LA CONFIGURATION ELECTRONIQUE LOCALE DANS LE SELENIUM TRIGONAL ET LE TELLURE TRIGONAL A PARTIR DE L’ANISOTROPIE DU D~PLACEMENT CHIMIQUE DE LA R.M.N. M. Benoussan Centre National d’Etudes des Télécommunications, 196, rue de Paris 92220 Bagneux. —
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Nous calculons le tenseur de déplacement chimique dans un modéle3 moléculaire en partant d’une deux déformée. L’introdjictionde hybridation l’un sp purement géométrique traduisant paramètres, l’écart entre les axes des orbitales liantes et les directions des liaisons, et l’autre fixant les positions relatives des niveaux énergétiques moléculaires, nous permet de rendre compte, dans le sélénium trigonal et dans le tellure, des résultats expérimentaux de
11.
ABSTRACTS OF PAPERS TO APPEAR IN J. PHYS. CHEM. SOLIDS
PHENOMEONOLOGICAL THEORY OF THE INTERACTION OF ELECTRONS WITH POLAR PHONONS IN ANISOTROPIC
13.
CRYSTALS E. Bergmann, Battelle Institute, Advanced Studies Center, CH-1227 Carouge-Geneva, Switzerland. The generalized phenomenological lattice equations of Huang are used to derive the Hamiltonian of the coupled electron phonon system in an anisotropic crystal. The dependence of the coupling constant on the angle formed by the phonon wave vector and the axis of an uniaxial crystal is given explicitly. A significant dependence of the coupling constant on this angle persists even in the case of dominant mechanical or electrostatic forces. Received 21 January 1974 Revised 12Apr11 1974
12.
THE ELECTRONIC CHARGE DENSITIES IN SEMICONDUCTING LAYER AND CHAIN STRUCTURES E. Mooser, I.Ch. SchlUter and M. Schlüter, Laboratoire de Physique Appliquée, Ecole Polytechnique Fédérale, Lausanne, Switzerland.
DIPOLAR INTERACTIONS IN RARE EARTH ORTHOFERRITES PART I: YFeO3 AND HoFeO3 R. Bidaux, J.E. Bouree and J. Hammann, Service de Physique du Solide et de Resonance Magnétique, Centre d’Etudes Nucléaires de Saclay, BP no 2 —91, Gif-sur-Yvette, France.
The part of dipolar interactions in the magnetic properties of YFeO3 and HoFeO3 is examined in detail. In YFeO3, one finds that the contribution of these interactions to the anisotropy in the xOz plane (easy magnetization plane for the iron moments) has the same order of magnitude as the crystalline anisotropy. In the case of HoFeO3, the molecular field formalism is used in order to interpret the existence of a single, ferromagnetic ordered structure for temperatures below a rearrangement temperature TR. The physical parameters introduced within the framework of this formalism are fitted by comparison with the available experimental results. Received 10 January 1974 Revised 18 March 1974 14.
From calculations of the pseudo-wavefunctions the charge densities of the valence electrons in the semiconducting crystals SnSe2, Pb12, GaSe, Se and Te have been determined. The results are compared with the valence bond description of semiconductors which can thus be confirmed and refined. Insight is gained into the accommodation in the valence bands of the excess s-electrons in PbI2 and GaSe. For Te the transformation from the trigonal to the simple cubic modification has been simulated on the computer. The changes of the charge densities occuring in this semiconductor-to-metal transition are discussed. Received 13 December 1973
Vol. 15, No.2
DETERMINATION DE LA CONFIGURATION ELECTRONIQUE LOCALE DANS LE SELENIUM TRIGONAL ET LE TELLURE TRIGONAL A PARTIR DE L’ANISOTROPIE DU D~PLACEMENT CHIMIQUE DE LA R.M.N. M. Benoussan Centre National d’Etudes des Télécommunications, 196, rue de Paris 92220 Bagneux. —
—
Nous calculons le tenseur de déplacement chimique dans un modéle3 moléculaire en partant d’une deux déformée. L’introdjictionde hybridation l’un sp purement géométrique traduisant paramètres, l’écart entre les axes des orbitales liantes et les directions des liaisons, et l’autre fixant les positions relatives des niveaux énergétiques moléculaires, nous permet de rendre compte, dans le sélénium trigonal et dans le tellure, des résultats expérimentaux de