Publications by authors named "I I Tupitsyn"
The disorder-to-order (crystallization) process in phase-change materials determines the speed and storage polymorphism of phase-change memory devices. Only by clarifying the fine-structure variation can the devices be insightfully designed, and encode and store information. As essential phase-change parent materials, the crystallized Sb-Te binary system is generally considered to have the cationic/anionic site occupied by Sb/Te atoms.
View Article and Find Full Text PDFArticle Synopsis
- Precise calculations of the dynamics in the homogeneous electron gas are crucial for designing and understanding new materials.
- A new diagrammatic Monte Carlo method is introduced to compute responses directly in the real frequency domain using Feynman diagrams, focusing on charge responses at moderate electron density.
- The findings help in extracting the frequency dependence of the exchange-correlation kernel, which is essential for improving time-dependent density functional theory in material dynamics, analogous to how ground state energies benefit density functional theory.
Building on previous developments [A. Taheridehkordi, S. H.
View Article and Find Full Text PDFThe strong mixing of close levels with two valence electrons in Be-like xenon greatly complicates ab initio QED calculations beyond the first-order approximation. Because of a strong interplay between the electron-electron correlation and QED effects, the standard single-level perturbative QED approach may fail, even if it takes into account the second-order screened QED diagrams. In the present Letter, the corresponding obstacles are overcome by working out the QED perturbation theory for quasidegenerate states.
View Article and Find Full Text PDFWe study how manifestations of strong electron-phonon interaction depend on the carrier concentration by solving the two-dimensional Holstein model for the spin-polarized fermions using an approximation free bold-line diagrammatic Monte Carlo method. We show that the strong electron-phonon interaction, obviously present at very small Fermion concentration, is masked by the Fermi blockade effects and Migdal's theorem to the extent that it manifests itself as moderate one at large carriers densities. Suppression of strong electron-phonon interaction fingerprints is in agreement with experimental observations in doped high temperature superconductors.
View Article and Find Full Text PDF