Structural Phase Stability and Electron-Phonon Coupling in Lithium
نویسندگان
چکیده
First-principles calculations of the free energy of several structural phases of Li are presented. The densityfunctional linear-response approach is used to calculate the volume-dependent phonon frequencies needed for computing the vibrational free energy within the quasiharmonic approximation. We show that the transformation from a close-packed structure at low temperatures to the bcc phase upon heating is driven by the large vibrational entropy associated with low-energy phonon modes in bcc Li. In addition, we find that the strength of the electron-phonon interaction in Li is strongly dependent on crystal structure. The coupling strength is significantly reduced in the low-temperature close-packed phases as compared to the bcc phase, and is consistent with the observed lack of a superconducting transition in Li. @S0163-1829~99!11905-2#
منابع مشابه
نقش دینامیک شبکه در ابررسانای La2-xBaxCuO4 به روش DFT
Electron-phonon coupling parameters are calculated for La2-x BaxCuO4 cuprate superconductor in a wide range of dopings, from undoped to overdoped compounds. In this study we aim to study the quality of such calculations based on DFT method so, the results of σ GGA+U electronic structure calculations are also investigated. The obtained value for electron-phonon coupling is in the same order of p...
متن کاملادغام الگوی شبکهای هولشتاین - کاندو برای توصیف نظریه ابررساناهای دمای بالا
It is a common knowledge that the formation of electron pairs is a necessary ingredient of any theoretical work describing superconductivity. Thus, finding the mechanism of the formation of the electron pairs is of utmost importance. There are some experiments on high transition temperature superconductors which support the electron-phonon (e-ph) interactions as the pairing mechanism (ARPES),...
متن کاملSuperconductivity of lithium-doped hydrogen under high pressure.
The high-pressure lattice dynamics and superconductivity of newly proposed lithium hydrides (LiH2, LiH6 and LiH8) have been extensively studied using density functional theory. The application of the Allen-Dynes modified McMillan equation and electron-phonon coupling calculations show that LiH6 and LiH8 are superconductors with critical temperatures (T(c)) of 38 K at 150 GPa for LiH6 and 31 K a...
متن کاملA ug 2 00 5 Electronic structure , electron - phonon coupling and superconductivity of isotypic noncentrosymmetric crystals Li 2 Pd 3 B and Li 2 Pt 3
Electronic structure of recently discovered isotypic ternary borides Li2Pd3B and Li2Pt3B, with noncentrosymmetric crystal structures, is studied with a view to understanding their superconducting properties. Estimates of the Fermi-surface averaged electron-phonon matrix element and Hopfield parameter are obtained in the rigid ion approximation of Gaspari and Gyorffy [Phys. Rev. Lett. 28 (1972) ...
متن کاملComparison of structural transformations and superconductivity in compressed sulfur and selenium
Density-functional calculations are presented for high-pressure structural phases of S and Se. The structural phase diagrams, phonon spectra, electron-phonon coupling, and superconducting properties of the isovalent elements are compared. We find that with increasing pressure, Se adopts a sequence of ever more closely packed structures (b-Po, bcc, fcc!, while S favors more open structures (b-Po...
متن کامل