290 citations · 1.6k across the 46 of their papers we have counts for
46 papers
Yttrium Superhydrides Revisited: Advanced Experimental and Theoretical Studies of YH, YH and YH
Dmitrii V. Semenok, Pedro N. Ferreira, Di Zhou +10
Yttrium polyhydrides are benchmark materials in high-pressure superconductivity, yet several key properties of the Y-H system remain insufficiently characterized. Here we combine c…
Assessing the possible superconductivity in doped perovskite hydride KMgH: Effects of lattice anharmonicity and spin fluctuations
Shaocong Lu, Ryosuke Akashi, Mitsuaki Kawamura +1
The superconducting properties of uniformly hole-doped perovskite hydride KMgH with varying doping concentration and lattice parameter corresponding to different pressures were…
Illuminating the Bragg intersections as roots of Dirac nodal lines and high-order van Hove singularities
Ryosuke Akashi
We theoretically reexamine nearly uniform electron models with weak crystalline potentials. In particular, we theorize the modulation of the plane-wave branches at linear regions w…
Semiconducting Electronic Structure of the Ferromagnetic Spinel Revealed by Soft-X-Ray Angle-Resolved Photoemission Spectroscopy
Hiroaki Tanaka, Andrei V. Telegin, Yurii P. Sukhorukov +12
We study the electronic structure of the ferromagnetic spinel by soft-x-ray angle-resolved photoemission spectroscopy (SX-ARPES) and first-p…
Lattice dielectric properties of rutile : First-principles anharmonic self-consistent phonon study
Tomohito Amano, Tamio Yamazaki, Ryosuke Akashi +2
We calculate the lattice dielectric function of strongly anharmonic rutile from ab initio anharmonic lattice dynamics methods. Since an accurate calculation of the…
A Noise-Robust Data Assimilation Method for Crystal Structure Prediction Using Powder Diffraction Intensity
Seiji Yoshikawa, Ryuhei Sato, Ryosuke Akashi +2
Crystal structure prediction for a given chemical composition has long been a challenge in condensed-matter science. We have recently shown that experimental powder X-ray diffracti…
Development of exchange-correlation functionals assisted by machine learning
Ryo Nagai, Ryosuke Akashi
With the recent rapid progress in the machine-learning (ML), there have emerged a new approach using the ML methods to the exchange-correlation functional of density functional the…
Machine-Learning-Based Exchange-Correlation Functional with Physical Asymptotic Constraints
Ryo Nagai, Ryosuke Akashi, Osamu Sugino
Density functional theory is the standard theory for computing the electronic structure of materials, which is based on a functional that maps the electron density to the energy. H…
The missing quantum number of the Floquet states
Cristian M. Le, Ryosuke Akashi, Shinji Tsuneyuki
We reformulate the Floquet theory for periodically driven quantum systems following a perfect analogy with the proof of Bloch theorem. We observe that the current standard method f…
Revisiting the homogeneous electron gas in pursuit of the properly normed ab initio Eliashberg theory
Ryosuke Akashi
We address an issue of how to accurately include the self energy effect of the screened electron-electron Coulomb interaction in the phonon-mediated superconductors from first prin…
Chemical physics of superconductivity in layered yttrium carbide halides from first principles
Ryosuke Akashi, Ryotaro Arita, Chao Zhang +2
We perform a thorough first-principles study on superconductivity in yttrium carbide halide YC (=Cl, Br, I) whose maximum transition temperature () amoun…
Superconductivity at 253 K in lanthanum-yttrium ternary hydrides
Dmitrii V. Semenok, Ivan A. Troyan, Alexander G. Kvashnin +14
Polyhydrides offer intriguing perspectives as high-temperature superconductors. Here we report the high-pressure synthesis of a series of lanthanum-yttrium ternary hydrides: cubic…
Coexistence of spontaneous polarization and superconductivity in hole-doped oxyhydrides ATiO_2H (A=K, Rb, Cs): first-principles study
Minjae Ghim, Nobuya Sato, Ryosuke Akashi +2
The polar metal is a material that hosts both polar distortion and metallicity. Such a material is expected to show exotic magneto-electric phenomena if superconducts. Here, we the…
First Principles Study of the Optical Dipole Trap for Two-Dimensional Excitons in Graphane
Hiroki Katow, Ryosuke Akashi, Yoshiyuki Miyamoto +1
Recent studies on excitons in two-dimensional materials have been widely conducted for their potential usages for novel electronic and optical devices. Especially, sophisticated ma…
Effect of spin fluctuations on superconductivity in V and Nb: a first-principles study
Kentaro Tsutsumi, Yuma Hizume, Mitsuaki Kawamura +2
We study the superconductivity in typical -band elemental superconductors V and Nb with the recently developed non-empirical computational scheme based on the density functional…
Defining a well-ordered Floquet basis by the average energy
Cristian M. Le, Ryosuke Akashi, Shinji Tsuneyuki
At the moment, the most efficient method to compute the state of a periodically driven quantum system is using Floquet theory and the Floquet eigenbasis. The wide application of th…
Spintronic superconductor in a bulk layered material with natural spin-valve structure
Shunsuke Sakuragi, S. Sasaki, R. Akashi +29
Multi-layered materials provide fascinating platforms to realize various functional properties, possibly leading to future electronic devices controlled by external fields. In part…
Relativistic density functional theory with finite-light-speed correction for the Coulomb interaction: a non-relativistic-reduction based approach
Tomoya Naito, Ryosuke Akashi, Haozhao Liang +1
The Breit correction, the finite-light-speed correction for the Coulomb interaction of the electron-electron interaction in , is introduced to density fu…
Archetypical "push the band critical point" mechanism for peaking of the density of states in three-dimensional crystals: Theory and case study of cubic HS
Ryosuke Akashi
The point of zero gradient of the electronic band structure--critical point--generally induces the singularity in the density of states (DOS), but no isolated critical point yields…
AtomREM: Non-empirical seeker of the minimum energy escape paths on many-dimensional potential landscapes without coarse graining
Yuri S. Nagornov, Ryosuke Akashi
Recently a non-empirical stochastic walker algorithm has been developed to search for the minimum-energy escape paths (MEP) from the minima of the potential surface [J. Phys. Soc.…
Coulomb Energy Density Functionals for Nuclear Systems: Recent Studies of Coulomb Exchange and Correlation Functionals
Tomoya Naito, Ryosuke Akashi, Gianluca Colò +2
The Coulomb exchange and correlation energy density functionals for electron systems are applied to nuclear systems. It is found that the exchange functionals in the generalized gr…
Completing density functional theory by machine-learning hidden messages from molecules
Ryo Nagai, Ryosuke Akashi, Osamu Sugino
Kohn-Sham density functional theory is the base of modern computational approaches to electronic structures. Their accuracy vitally relies on the exchange-correlation energy functi…
Non-empirical weighted Langevin mechanics for the potential escape problem: parallel algorithm and application to the Argon clusters
Yuri S. Nagornov, Ryosuke Akashi
Recently a non-empirical stochastic walker algorithm has been developed to search for the minimum-energy escape paths (MEP) from the minima of the potential surface [J. Phys. Soc.…
First-principles study of phonon anharmonicity and negative thermal expansion in ScF3
Yusuke Oba, Terumasa Tadano, Ryosuke Akashi +1
The microscopic origin of the large negative thermal expansion of cubic scandium trifluorides (ScF3) is investigated by performing a set of anharmonic free-energy calculations base…