摘要:

I give a brief sketch of the current status of QCD and of prospects over the next few years, anticipating the development of teraflop scale computers.

ISSN:0094-243X    

DOI:10.1063/1.42623

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Among the large problems for which teraflop (in principle massively parallel) machines will provide the means of solution are those involving the prediction of gravitational wave amplitudes from interacting strong field gravitational situations. Examples are neutron star/neutron star, neutron star/black hole, and black hole/black hole interactions, collisions, and mergers.While the weak field, long distance behavior of the gravitational field can be well treated by approximate methods, the strong field interaction and radiation regimes is full 3‐dimensional numerical analysis, apparently on grids of order (1000)3. Variable count amounts typically to about 80 variables per zone. Based on smaller scale evolutions running at about 0.2 to 0.3 Gflop/sec (Cray Y‐MP) which require ∼2×10−5seconds per zone cycle, one deduces ∼2×104seconds per cycle ∼6 hours/cycle for (1000)3(7×1011Bytes of memory required) runs. Because a typical run would require ∼104cycles, CPU times in decades would be required at Y‐MP CPU rates. Howevere, teraflop sustained machines would reduce this to the 6–10 hour range, and algorithm improvements would be expected to lower this by another factor of 10 (at least). Since there are a number of feasible designs for teraflow/sec machines, it appears the 2‐black hole problem will be double within the next five years or so. This paper discusses an outline for designing the code, discusses various alternatives in approach, and drafts a possible path through the forest of alternatives.

ISSN:0094-243X    

DOI:10.1063/1.42616

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We present a cursory review of the new developments of the finite temperature molecular dynamics approach along with some selected applications.

ISSN:0094-243X    

DOI:10.1063/1.42602

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

By sampling the exact many‐body ground state via a second order Diffusion Monte Carlo algorithm, we show how the collective excitation spectrum, transition densities, and the dynamic structure functions of4He clusters can be determined variationally by solving a generalized Feynman eigenvalue equation.

ISSN:0094-243X    

DOI:10.1063/1.42609

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Particle production via two‐photon processes in relativistic heavy‐ion colliders is discussed. We consider the coherent production, including its impact parameter dependence, and incoherent production. Particular attention is given to Higgs boson production in the energy regime of the LHC and the SSC.

ISSN:0094-243X    

DOI:10.1063/1.42610

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Pursuing a many‐nucleon description of collective rotations of nuclei demands that very large sparse matrix representations of hamiltonians be constructed and diagonalized. Two general computational methods are presented for reducing the computer resources required for these processes. Specifically, a space and time optimal numerical database called a Weighted Search Tree that minimizes the number of redundant intermediate calculations required when calculating the matrix elements of the sparse hamiltonian matrices is given, and a matrix multiplication algorithm for a new space optimal optimal representation for sparse matrices is given which is expected to dramatically decrease the cost of diagonalizing large sparse band matrices. Both methods can be implemented in a broad range of large‐scale scientific applications.

ISSN:0094-243X    

DOI:10.1063/1.42611

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Computational techniques of energies and widths of metastable states are discussed when Siegert boundary conditions are applied to solutions of Schro¨dinger’s eigenvalue equation in order to achieve the necessary analytic continuation onto the complex energy plane. Results for a number of different potentials are presented to illustrate specific technical problems.

ISSN:0094-243X    

DOI:10.1063/1.42612

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

Results are presented showing recent progress in the momentum space computation of atomic and nuclear Gamow states. Coupled bound and reaction channels and an exact treatment of the Coulomb plus nuclear potentials are included. Three–dimensional visualizations help uncover some of the physics present on the complex energy sheets.

ISSN:0094-243X    

DOI:10.1063/1.42613

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

We review some of the recent progress in the studies of alkaline‐earth, negative ions. Computations of autodetachment rates, electron affinities and transition wavelengths are discussed and some new and improved results are given.

ISSN:0094-243X    

DOI:10.1063/1.42625

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The construction of Lorentz covariant three‐body states and their angular momentum decomposition is reviewed. It is shown how they can be used to construct the impulse approximation to the optical potential in momentum space. The potential thus constructed incorporates covariant kinematics, relativistic normalizations and phase space factors, a covariant treatment of the recoil of the target nucleus, utilizes invariant amplitudes which are free of kinematic singularities, and allows an exact performance of the fermi integration over the momentum of the struck nucleon. The interaction of the K+meson with12C and40Ca is examined and it is found that the present data indicate an enhanced, in‐medium, two‐body interaction. We find that all the data is consistent with an angle and energy independent 25% enhancement of the theoretical calculations.

ISSN:0094-243X    

DOI:10.1063/1.42614

出版商:AIP    

年代:1992

数据来源: AIP