computational science an emerging multi-disciplinary research area that involves the use of high...

Computational Science

An emerging multi-disciplinary research area that involves the use of high performance computers to study scientific problems.

School of Computer Science

April 2002

The availability of high performance computers, graphic

workstations, and high-speed networks, coupled with major

advances in algorithms and software, has brought about a

revolution in the way scientific and engineering

investigations are carried out.

Computational scientists seek

to gain an understanding of

science principally through the

development, use and

analysis of mathematical

models on high performance

computers .

Cray T3E

Origin 3000

Computational ScienceHigh Performance Scientific ComputationThe Motivation

Electron-atom and electron-molecule collisions drive many of the key chemical and physical processes in important environments that range from plasmas to living tissue.

Most energy deposited in cells by ionizing radiation is channelled into free secondary electrons with energies between 1 eV and 20 eV(B. Boudaïffa et al., Science 287 (2000) 1658)

Secondary electrons produced by fast ion tracks in radioactive waste

Computational ScienceHigh Performance Scientific ComputationThe Motivation

Studying these electron-driven processes provides a microscopic understanding of reactions in these environments and thus helps advance many technologies that are based on these processes.

Plasma flat panel display (Fujitsu

Corp.)

Computational ScienceHigh Performance Scientific ComputationThe Physics

ground state

e- + Ai(N+1)

e- + A*j(N+1)

2e- + A+k(N)

continuum

ionizationthreshold

Electron impact excitationand ionization

r N+1

Internalregion

R-matrix Approach

Externalregion

Computational ScienceHigh Performance Scientific ComputationThe Model

Schrödinger Equation solved using propagation techniques.

(HN+1 - E)N+1 = 0

Internal Region

In each sector:

• Construct Hamiltonian matrix;• Diagonalize Hamiltonian matrix.

Propagate global R-matrix across 2-D plane.

External RegionSolve systems of coupled 2nd order inhomogeneous ODEs - propagate across a 1-D plane.

Computational ScienceHigh Performance Scientific ComputationThe Computation - internal region

Gather surface amplitudes and distribute to other processors in cluster.

Global R-matrix Store

Surface amplitudes

Gather global R-matrix from processors in cluster and store.

Compute local R-matrices.

Propagate global R-matrix.

Repeat for next energy.




Surface amplitudes





Surface amplitudes



Surface amplitudes


Surface amplitudes


Gather global R-matrix from processors in cluster and store.Repeat for next energy.




Surface amplitudes





Computational ScienceHigh Performance Scientific ComputationThe Computation - external region

DO J = 1, NCHAN ETJ = ET(J) JOC = 0 IF (ETJ .LT. ZERO) JOC = 1 SKJ = SQRT(ABS(ETJ)) S2K = TWO*SKJCC INITIALISE THE RECURRENCE C DO I = 1, NCHAN DO IP1 = 1, NTASY W1(I, IP1) = ZERO W2(I, IP1) = ZERO ENDDO ENDDO IF (JOC .EQ. 1) THEN W2(J, 1) = ONE ELSE W1(J, 1) = ONE ENDIF

Computational ScienceInternational Software Library

GOBACK = .FALSE. TEMPX = X DO I = 1, NCHAN K = I*(I - 1)/2 DO J = 1, I TEMPK(I, J) = Y(J + K) TEMPK(J, I) = Y(J + K) ENDDO ENDDO ELSE

R(NOPTS) = X GOBACK = .FALSE. DO I = 1, NCHAN K = I*(I - 1)/2 DO J = 1, I KBAR(NOPTS, I, J) = Y(J + K) KBAR(NOPTS, J, I) = Y(J + K) ENDDO ENDDO


With the aid of a grant from the then UK Science Research Council the Computer Physics Communications International Program Library (CPCPL) was established at Queen's University Belfast in 1969.

Now an integral part of the Elsevier Science Journal, Computer Physics Communications, the Library continues to make a significant international contribution to research through its role of storing and disseminating refereed computer programs whose descriptions have been published in the journal Computer Physics Communications.


CPCPL currently holds over 1,800 computer programs contributed by scientists world-wide. Catalogued under twenty-three headings the programs represent a major international repository of computational knowledge and technique.

•Astronomy and Astrophysics•Atomic Physics•Biology and Molecular Biology•Computational Methods•Computer Algebra•Computer Languages, Hardware and Software•Condensed Matter and Surface Science•Crystallography•Databases•Electrostatics and Electromagnetics•Elementary Particle Physics•Gases and Fluids•Geophysics

•Graphics•Laser Physics•Molecular Physics and Physical Chemistry•Nuclear Physics•Optics•Plasma Physics•Programming and Publication Practice•Radiation•Reactor Systems•Statistical Physics & Thermodynamics

computational science an emerging multi-disciplinary research area that involves the use of high...

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