A first-principles study of theoretical superconductivity on RbH by doping without applied pressure.

The structural, electronic, lattice dynamics, electron-phonon (el-ph) coupling, and superconducting (SC) properties of the alkali-metal hydride RbH, metallized through electron-doping by the construction of the solid-solution Rb1-xSrH, are systematically analyzed as a function of Sr-content within the framework of density functional perturbation and Migdal-Eliashberg theories, taking into account the effect of zero-point energy contribution by the quasi-harmonic approximation. For the entire studied range of Sr-content, steady increments of the el-ph coupling constant and the SC critical temperature are found with progressive alkaline-earth metal content through electron-doping, reaching the values of = 1.92 andTc=51.

Electron- and hole-doping on ScHand YH: effects on superconductivity without applied pressure.

We present the evolution of the structural, electronic, and lattice dynamical properties, as well as the electron-phonon (el-ph) coupling and superconducting critical temperature () of ScHand YHmetal hydrides solid solutions, as a function of the electron- and hole-doping content. The study was performed within the density functional perturbation theory, taking into account the effect of zero-point energy through the quasi-harmonic approximation, and the solid solutions ScMH(M = Ca, Ti) and YMH(M = Sr, Zr) were modeled by the virtual crystal approximation. We have found that, under hole-doping (M = Ca, Sr), the ScHand YHhydrides do not improve their el-ph coupling properties, sensed by().

Comparing two high correlation models to test the mechanical stability of americium-II.

In this work two high density functional theory (DFT) correlation methodologies, the so called DFT+U (or GGA+U) implementation and the exact exchange of correlated electrons (EECE), hybrid DFT functional (or one case of hybrid DFT), are tested to determine the mechanical properties of americium-II. For each case, the numeric value of their principal parameter is chosen ([Formula: see text] for the first case and [Formula: see text] for the second one) once the crystalline structure meets all the mechanical stability conditions. The results show that there is a range of values of [Formula: see text] and [Formula: see text] in which both methodologies generate a stable (experimentally correct) non-magnetic ground state, reaching approximately the same numeric value of the set of elastic constants of the cubic structure.

Effect of doping on lattice dynamics and electron-phonon coupling of the actinides Ac-Th alloy.

We have studied the electronic, lattice dynamical, and electron-phonon properties of the actinides [Formula: see text]Th alloy within the framework of density functional perturbation theory. The self-consistent virtual crystal approximation is used for the alloy modeling, and spin-orbit coupling is included in the calculation of all relevant quantities. An overall decrease of the electron-phonon coupling (λ) by [Formula: see text] from Ac to Th was observed.

Effects of electron doping on the stability of the metal hydride NaH.

Alkali and alkali-earth metal hydrides have high volumetric and gravimetric hydrogen densities, but due to their high thermodynamic stability, they possess high dehydrogenation temperatures which may be reduced by transforming these compounds into less stable states/configurations. We present a systematic computational study of the electron doping effects on the stability of the alkali metal hydride NaH substituted with Mg, using the self-consistent version of the virtual crystal approximation to model the alloy Na Mg H. The phonon dispersions were studied paying special attention to the crystal stability and the correlations with the electronic structure taking into account the zero point energy contribution.