H_(3)Se in the Imˉ3m Phase:High-Pressure Superconductor with T_(c) Reaching 200K at 64GPa Mediated by Anharmonic Phonons

Hydrogen-based compounds have attracted significant attention in recent years due to the discovery of conventional superconductivity with high critical temperature under high pressure,rekindling hopes for finding roomtemperature superconductors.In this study,we investigated the vibrational and superconducting properties of H_(3)Sein the Im￣3m phase under pressures of 50-200GPa.Our approach combines the stochastic self-consistent harmonic approximation and first-principles calculations to account for the quantum and anharmonic effects of ions.According to the results,these effects significantly modify the crystal structure,increasing the inner pressure by approximately 8GPa compared to situations in which they are ignored.The phonon spectra suggest that when these effects are considered,the crystal stabilizes at pressures as low as approximately 61GPa,which is significantly lower than the previously predicted value of over 100GPa.Our calculations also highlight the critical role of quantum and anharmonic effects on the electron-phonon coupling properties.Neglecting these factors can result in a significant overestimation of the superconducting critical temperature(T_(c))by approximately 4K(200GPa)to 25K(125GPa).With anharmonic phonons,the T_(c) calculated from the Migdal-Eliashberg equations reaches 200K(μ⋆=0.1,λ=4.1)as the pressure decreases to 64GPa,indicating that the crystal is a rare high-Tc superconductor at moderate pressures.

Broadening the phenotype of m.5703G>A mutation in mitochondrial tRNAAsn gene from mitochondrial myopathy to myoclonic epilepsy with ragged red fibers syndrome

To the Editor:Mutations in mitochondrial DNA(mtDNA)cause mitochondrial diseases with multisystem involvement and variable clinical phenotypes.Myoclonic epilepsy with ragged red fiber(MERRF)syndrome is characterized by myoclonus,generalized epilepsy,cerebellar ataxia,and mitochondrial myopathy with ragged red fibers(RRFs).Other features include hearing impairment,psychiatric disorders,and dysarthria.