Atomic Physics with Supercomputers

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Atomic Physics with Supercomputers
Darío M. Mitnik
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Electron-Ion scatteringcalculations
Darío M. Mitnik
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Atomic Physics with Supercomputers
Darío M. Mitnik
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M. S. Pindzola, F. Robicheaux, J.
Colgan, Auburn University, Auburn, AL D. C.
Griffin, Rollins College, Winter Park, FL N. R.
Badnell Strathclyde University, Glasgow, UK
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Outline

• What are we calculating?

• Why do we need supercomputers for such
  calculations?

• How do we use the supercomputers in these
  calculations?

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What are we calculating?

• Cross Sections

• Rate Coefficients

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Electron-Impact Excitation
N-electron ion
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Electron-Impact Excitation
ltyafi V ybff gt
yb
ff
ya
fi
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Electron-Impact Ionization
(N-1) electron ion
ki
EI
ya
N electron ion
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Electron-Impact Ionization
ltyafi V feff gt
fe
ff
ya
fi
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Radiative Recombination
ya
yb
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Radiative Recombination
Photoionization
Mba ltyb D yafi gt
ya fi
yb
w
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Dielectronic Recombination
Photoionization
Mba ltyb D yafi gt
ya fi
yb
w
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Dielectronic Recombination
ya
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Dielectronic Recombination
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Dielectronic Recombination
D.M. Mitnik et al, Phys. Rev. A 61, 022705 (2000)
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Dielectronic Recombination
D.M. Mitnik et al, Phys. Rev. A 57, 4365 (1998)
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Electron-ion Recombination
D.M. Mitnik et al, Phys. Rev. A 59, 3592 (1999)
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Excitation-Autoionization
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Excitation-Autoionization
D.M. Mitnik et al, Phys. Rev. A 53, 3178 (1996)
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Excitation (resonances)
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Excitation (resonances)
D.M. Mitnik et al, Phys. Rev. A 62, 062711 (2000)
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Excitation (resonances)
D.C. Griffin et al, J. Phys. B 33, 4389 (2000)
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Why supercomputersin Atomic Physics?

• only a few atomic physicists are using
  supercomputers

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Why supercomputersin Atomic Physics?

• T. R. Rescigno et al., Science 286, 2474 (1999).

• M. S. Pindzola and F. Robicheaux, Phys. Rev. A
  54, 2142 (1996).

• Collisional breakup in a quantum system of three
  charged particles

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Electron-Impact Ionization of Hydrogen
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Methods
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Time-independent R-matrix method
P. G. Burke and K. A. Berrington
27 key papers reprinted
Short Bibliography list
547 references
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Time-independent R-matrix method
Internal Region
External Region
a
Y sin(kr) Kcos(kr)
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Why supercomputers?
Size of (N1)-Hamiltonian MXMAT MZCHF x MZNR2
MZNC2
158 x 50 100 8000 512 Mb
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Why supercomputers?

• Thousands of points are needed
• in order to map the narrow resonances.

D.C. Griffin et al, J. Phys. B 33, 4389 (2000)
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Time-Dependent method
Time-dependent Schrodinger equation
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Time-Dependent method
Time-dependent close-coupled equation
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Why supercomputers?
16 x 250 x 250 1000000
250 x 250 62500
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Why supercomputers?

• Time

• Memory

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What is a supercomputer?

• Shared-Memory

• Distributed-Memory

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Glossary

• parallelization

• functional parallelism

• data parallelism

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Example of data parallelism

• we have 10000 cards
• we want to pick up the highest card
• each comparison takes 1 second

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Example of data parallelism
Time (sec)
Processors
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Example of a simple program
print, hello world stop end
call mpi_init call mpi_ rank(iam,nproc) print,
hello world, from process ,iam call
mpi_finalize stop end
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Example of a simple program
hello world
hello world, from process 2 hello world, from
process 0 hello world, from process 4 hello
world, from process 1 hello world, from process
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The R-matrix I package

• Inner-Region
• STG1 calculates the orbital basis and all
  radial integrals
• STG2 calculates LS-coupling matrix elements.
  solves the N-electron problem.
  sets the (N1)-electron Hamiltonian
• STG3 diagonalizes the (N1)-electron
  Hamiltonian in the continuum basis

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The R-matrix I package

• Outer-Region
• STGF solves the external-region coupled
  equations.
• STGICF calculates level-to-level collision
  strengths by doing
  an intermediate- coupling frame
  transformation.

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Diagonalization Timing
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Example
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Parallelization of the external-region codes
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Time-Dependent method
Time-dependent Schrodinger equation
Time evolution of a single-channel
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Time-Dependent method
Initial condition for the solution
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Initial condition for the solution
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Time-Dependent method
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Propagated wavefunction
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Time-Dependent method
Projection of the wavefunction
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Parallelization of the time-dependent codes
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Conclusions

• Atomic Physics is still alive

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