A5081021731- Nuclear physics research studies
- Laser-Matter Interactions and Applications
- Advanced Chemical Physics Studies
- Spectroscopy and Quantum Chemical Studies
- Advanced Fiber Laser Technologies
- Atomic and Molecular Physics
- Laser Material Processing Techniques
- Quantum Chromodynamics and Particle Interactions
- Diamond and Carbon-based Materials Research
- Nuclear Physics and Applications
- Quantum, superfluid, helium dynamics
- Photonic and Optical Devices
- Plasmonic and Surface Plasmon Research
- Laser-induced spectroscopy and plasma
- Cold Atom Physics and Bose-Einstein Condensates
- Ion-surface interactions and analysis
- Nuclear reactor physics and engineering
- Fullerene Chemistry and Applications
- Mechanical and Optical Resonators
- Molecular Junctions and Nanostructures
- Quantum chaos and dynamical systems
- Photochemistry and Electron Transfer Studies
- 2D Materials and Applications
- Graphene research and applications
- Astronomical and nuclear sciences
University of Tsukuba
2015-2024
National Defense Academy of Japan
2024
Kansai Photon Science Institute
2016-2023
National Institutes for Quantum Science and Technology
2023
Australian National University
2022
Kobe University
2021
Max Planck Institute for the Structure and Dynamics of Matter
2019
RIKEN Nishina Center
2009-2016
Japan Atomic Energy Agency
2016
RIKEN
2012
We study the dipole response of atomic clusters by solving equations time-dependent local-density approximation in real time. The method appears to be more efficient than matrix or Green's function methods for large modeled with realistic ionic pseudopotentials. As applications method, we exhibit results sodium and lithium ${\mathrm{C}}_{60}$ molecules. calculated Mie resonance ${\mathrm{Na}}_{147}$ is practically identical that obtained jellium approximation, leaving origin redshift...
Electron transfer from valence to conduction band states in semiconductors is the basis of modern electronics. Here, attosecond extreme ultraviolet (XUV) spectroscopy used resolve this process silicon real time. Electrons injected into by few-cycle laser pulses alter XUV absorption spectrum sharp steps synchronized with electric field oscillations. The observed ~450-attosecond step rise time provides an upper limit for carrier-induced band-gap reduction and electron-electron scattering band....
Shining a fast light on diamonds Conceptually, the electronic structure of matter is fixed scaffold energy levels, which electrons climb with help absorption. In reality, light's electromagnetic field distorts scaffold, phenomenon that becomes increasingly evident rising intensity. Lucchini et al. studied manifestation this phenomenon, termed dynamical Franz Keldysh effect, in diamond substrates exposed to sudden, moderately intense infrared fields. Using attosecond probe pulses and...
We apply the coupled dynamics of time-dependent density functional theory and Maxwell equations to interaction intense laser pulses with crystalline silicon. As a function electromagnetic field intensity, we see several regions in response. At lowest intensities, pulse is reflected transmitted accord dielectric response, characteristics energy deposition consistent two-photon absorption. The absorption process begins deviate from that at intensities ~ 10^13 W/cm^2, where deposited order 1 eV...
We present the basic concepts and recent developments in time-dependent density functional theory (TDDFT) for describing nuclear dynamics at low energy. The symmetry breaking is inherent energy functionals (EDFs), which provides a practical description of important correlations ground state. Properties elementary modes excitation are strongly influenced by can be studied with TDDFT. In particular, number linear response calculation have demonstrated their usefulness collective nuclei....
High-order-harmonic generation by a highly nonlinear interaction of infrared laser fields with matter allows for the attosecond pulses in XUV spectral regime. This process, well established atoms, has been recently extended to condensed phase. Remarkably well-pronounced harmonics up order $\ensuremath{\sim}30$ have observed dielectrics. We establish route toward an ab initio multiscale simulation solid-state high-order-harmonic generation. find that mesoscopic effects system, particular...
We present an algorithm to calculate the linear response of periodic systems in time-dependent density functional thoery, using a real-space representation electron wave functions and calculating dynamics real time. The formulation increases efficiency for interaction, real-time treatment decreases storage requirements allows entire frequency-dependent be calculated at once. give as examples dielectric simple metal, lithium, elemental insulator, diamond.
Abstract We review our methods to calculate optical response of molecules in the linear time‐dependent density‐functional theory. Three distinct formalisms which are implemented three‐dimensional grid representation explained detail. They real‐time method solving Kohn–Sham equation time domain, modified Sternheimer calculates an external field fixed frequency, and matrix eigenvalue approach. also illustrate treatments scattering boundary condition, needed accurately describe photoionization...
We present a first-principles calculation for an optical dielectric breakdown in diamond, which is induced by intense laser field. employ the time-dependent density-functional theory solving Kohn--Sham equation real time and space. For low intensities, ionization agrees well with Keldysh formula. The shows qualitative change of electron dynamics as intensity increases, from screening at intensities to above $7\ifmmode\times\else\texttimes\fi{}{10}^{14}\text{ }\text{W}/{\text{cm}}^{2}$....
Multinucleon transfer processes in heavy-ion reactions at energies slightly above the Coulomb barrier are investigated a fully microscopic framework of time-dependent Hartree-Fock (TDHF) theory. Transfer probabilities calculated from TDHF wave function after collision using projection operator method which has recently been proposed by Simenel [Phys. Rev. Lett. 105, 192701 (2010)]. We show results calculations for cross sections...
We propose a practical method to solve the random-phase approximation (RPA) in self-consistent Hartree-Fock (HF) and density-functional theory. The is based on numerical evaluation of residual interactions utilizing finite amplitude single-particle wave functions. only requires calculations Hamiltonian constructed with independent bra ket states. Using present method, RPA calculation becomes possible little extension code static HF calculation. demonstrate usefulness accuracy performing test...
We present simple equations for a canonical-basis formulation of the time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory. The are obtained from TDHFB theory with an approximation that pair potential is assumed to be diagonal in canonical basis. significantly reduces computational cost. apply method linear-response calculations even-even light nuclei and demonstrate its capability accuracy by comparing our results recent quasi-particle random-phase Skyrme functionals. show systematic...
We theoretically investigate the generation of ultrafast currents in insulators induced by strong few-cycle laser pulses. Ab initio simulations based on time-dependent density functional theory give insight into atomic-scale properties current signifying a femtosecond-scale insulator-metal transition. observe transition from nonlinear polarization during pulse at low intensities to tunnelinglike excitation conduction band higher intensities. At high intensities, persists after conclusion...
The authors performed extensive simulations for the ${}^{64}$Ni + ${}^{238}$U reaction, which is a promising candidate synthesizing superheavy element 120. They place special emphasis on effects of nuclear deformation and shell structure quasifission dynamics, prevents fusion colliding nuclei. suggest an interesting possibility, that 120 may be synthesized with high probability when collides side-on at higher incident energies than in past experiments.
The time-dependent local-density approximation (TDLDA) is applied to the optical response of conjugated carbon molecules in energy range 0–30 eV, with calculations given for chains, polyenes, retinal, benzene, and C60. major feature spectra, collective π–π* transition, seen at energies ranging from below 2 7 eV reproduced by theory a few tenths an electron volt good account systematic trends. However, there some indication that TDLDA predicts too much fragmentation strength function large...
The continuum random-phase approximation is extended to the one applicable deformed nuclei. We propose two different approaches. One based on use of three-dimensional (3D) Green's function, and other small-amplitude TDHF with absorbing boundary condition. Both methods are 3D Cartesian grid representation systems no symmetry nuclear shape. accuracy identity these examined BKN interaction. Using full Skyrme energy functional in approach, we study isovector giant dipole states for...
The pygmy dipole resonances (PDR) for even-even nuclei in $8\ensuremath{\leqslant}Z\ensuremath{\leqslant}40$ are studied performing a systematic calculation of the random-phase approximation with Skyrme functional SkM*. is fully self-consistent and does not assume any symmetry nuclear shape ground state. In every isotopic chain, PDR emerges by showing peak $E1$ strength at energies less than 10 MeV. strongly depends on position Fermi level shows clear correlation occupation orbits orbital...
We calculate the dielectric response of crystalline silicon following irradiation by a high-intensity laser pulse, modeling dynamics time-dependent Kohn-Sham equations in presence field. Pump-probe measurements are numerically simulated including both pump and probe externals fields simulation. As expected, excited shows features an electron-hole plasma nonequilibrium phase its response, characterized negative divergence real part function at small frequencies. The to pulse depends on...
Recent developments in attosecond technology led to tabletop X-ray spectroscopy the soft range, thus uniting element- and state-specificity of core-level x-ray absorption with time resolution follow electronic dynamics real time. We describe recent work investigations into materials such as Si, SiO2, GaN, Al2O3, Ti, TiO2, enabled by convergence these two capabilities. showcase state-of-the-art on isolated pulses for near edge (XANES) observe 3d-state semi-metal TiS2 at Ti L-edge (460 eV)....