External Review on Center for Computational Sciences
University of Tsukuba
2007.10.30-11.1

Activities and Collaborations 8
Division of Materials and Life Sciences

Quantum Many-Body Systems GroupK. Yabana

Quantum Many-Body Systems Group

Members and research interests
Atomic Nuclei

Atoms, Molecules

Composed of protons and neutrons
strong interaction

SolidsComposed of electrons and ions
Coulomb interaction

Nuclear Physics
K. YabanaY. Hashimoto
T. Nakatsukasa ( -2007.7)

Common tool:
Quantum dynamics,
Wave mechanical simulation

K. Hino ( -2007.3)
H. Koizumi
X.-M. Tong (2005.10- )Atomic Physics
Material ScienceComputational Quantum Dynamics
Computational Optical Sciences
Morning session: Yabana, Nakatsukasa
Time-dependent Density-Functional Theory (TDDFT)⎧ h2 r 2r ⎫ rr∂∇ + Veff ( r , t )⎬ψ i ( r , t ) = ih ψ i (r , t )
⎨−∂t
⎩ 2m
⎭
Real-space 3-dim grid representation
Real-time evolution of the wave function

ψ m (xi , y j , z k , tl )3 topics
1. Electronic dynamics under laser field
2. Nuclear density-functional theory
3. Developing real-time, real-space code

Afternoon parallel session: Tong, Koizumi, Hashimoto

Atoms, molecules, solid under intense, ultra-short pulse laser
One of the frontiers in current laser scienceseE(t)zz

Laser intensity: 1013-1015W/cm2
laser electric field is comparable
to field inside materials

Ethylene molecule underintense laser field- Tunnel ionization,- rescattering,- high harmonic generation

Nonlinear, nonperturbative naturein electron dynamics
Time resolution offemto (10-15s) to atto (10-18s)-second
will be discussed by X.-M. Tong

TDDFT calculation

Laser Induced breakdown in dielectricsFemtosecond laser machining
Non-thermal, precise cutting technique
M.D. Perry et.al,
J. Appl. Phys. 85, 6803 (1999)

1.4 ns350 fs

We have achieved
First-principles Electron Dynamics Simulation-First calculation of electron dynamics in solid
under intense pulse laser-First demonstration of optical breakdown
within the time-dependent density-functional theory

Applied external field Eext(t)Insulator

Pulse laser

Collaboration with JAEA

Irradiation of intense, ultra-short pulse laser on dielectrics
Calculations are achieved partly on PACS-CS.

Laser pulse
Dielectrics-1Excitation energy [eV atom ]Energy transfer from laser to electrons

Electric Field [eV/nm]

100

Eext照射レーザー電場
(t)
物質内電場

50
0-50Etot(t)Energy [eV/atom]-100
5101010-1

101020Time [fs]

30

TDDFT

-52ΔE∝CI-7
12101310141510

16102

Energy transfer
From laser
toレーザー光から電子へのelectrons
エネルギー移行

2

Optical breakdown
7x1014 W/cm2 (16fs)-3

103Frequency 3.1 eV

Keldysh theory

1040110Irradiance [W/cm ]402 photon absorption
Keldysh theory (1965)

Intensity I = 3.5×1014 ( W/cm2 )Frequency ω = 0.5 (eV)Electric Field (a.u.)Electron dynamics inside bulk material

0

Total electron density （１１０）102030Time (fs)40

Density difference from ground state （１１０）

Calculation: J.-I. IwataDensity functional theory for nuclear structure
protonNucleineutron- Quantum liquid of two kinds of fermions(protons and neutrons)
Nuclear force- Strong interaction

10-15m

Success of density functional theory forMasses

ShapesExcitations

Current hot issues:
1. How and where the elements (nuclei) are created?
2. Find universal nuclear energy density functional of nuclei.
(UNEDF project, SciDAC, Yabana and Nakatsukasa take part in as foreign collaborator.)- First principle calculation of nuclear force. (Ishii, Aoki)- Green function Monte Carlo for light nuclei (Argonne, USA)
- Phenomenological construction of energy functional.

RIBF at RIKEN (T. Nakatsukasa, 2007.8-)(Radioactive Ion Beam Factory, 2007-)

Shape, excitation (optical response), and density-functional.
TDDFT for electronic and nuclear systems
Nuclear density-functional

16O

18Osphericalprolate

24Mg

26Mg

prolatetriaxial

Electronic density-functional
for molecules
100CalCal

80ExpExp60
402000204002040

Photon energy [ eV ]Optical absorption of organic molecule,C3H6

Toward “Computational Nuclear Data Table”

protons

First attempt for comprehensive calculationfor optical responses of atomic nuclei (PACS-CS)

SkM*
Rbox= 15 fm
Γ = 1 MeV
neutrons

1 day / (nuclei, 256CPU)

Systematic investigation

CBeO
Ne

Peak position

Si S ArMg
Cal. vs. Exp.
Peak splitting
by deformation
14C
22Ne

Excitation energy too low(indication for energy
density functional)

Computation for large systems:
developing efficient MPI code for massively-parallel machine
under cooperation with- computational condenced matter group (real-space DFT code)- high performance computing groupr⎧⎪ h 2 r 2r rr
rr ⎫⎪ rrn(r', t)∂2∇ + ∑ Vion (r − Ra ) + e ∫ dr ' r r + μ xc (n(r , t )) + Vext (r , t )⎬ψ i (r , t ) = ih ψ i (r , t )⎨−r − r'∂t⎪⎩ 2m⎪⎭aψ m (xi , y j , z k , tl )orbital parallel- Simple coding- Communication among whole processors
in constructing density from orbitals.

space division- communication only with adjacent processors- good balance among processors

１CPU

Present status of space-division parallel
N2 molecule# of grid points# of CPU# of time step

5 orbitals
303/CPU256 = 4x8x8
10,000１CPU⎧ h2 r 2r ⎫ rr∂
∇ + V (r , t )⎬ψ i (r , t ) = ih ψ i (r , t )⎨−∂t⎩ 2m⎭

Computationaltime

Communicationtime (adjacent)h2−Δψ m ( x , y , z , t )2m

959 s(23.9%)

333 s(8.3%)V ( x, y, z , t )ψ m ( x, y, z , t )306 s(7.6%)

102 s(2.5%)Δφ ( x, y, z ) = −4πρ ( x, y , z )1290 s(32.2%)

227 s(5.7%)

Communication
time (Allreduce)

378 s(9.4%)In total, computation 71.2% + communication 28.8%

Example:Coulomb explosion of fullerene (C60)
under intense laser pulse

Summary
Quantum Many-Body Systems Group- Quantum dynamics simulation- Computational optical sciences

Particle physics
Lattice QCD
Nuclear force

Astrophysics
Origin of elements
Evolution of stars

Condenced matter physics
High performance computing- Real-time, -space DFT
Efficient parallel code

Time-dependent
density-functional theory
Nuclearsystems- construct DF- systematics

Electronicsystems- Intense field- excited states
Computational Life Sciences- Excited states, Opticalresponse of bio-molecules- Electron dynamics in XFEL