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Inhaltsverzeichnis

Frontmatter

Supercomputers — The Situation Today

Abstract
The current situation in the super- and mini supercomputer market is changing rapidly. New manufacturers try to place high-performance computers in the market and well known vendors stop their activities in supercomputing. The performance of these new supercomputers and the distribution of the machines by countries and institutions is dicussed. A list of the supercomputers installed in Western Germany is included.
U. Harms

Graphic Supercomputing on the Ardent and Stellar Graphics Supercomputers

Abstract
Both the size of scientific and engineering problems and the quantity of data generated present a large challenge to researchers: namely, how to understand the results of their computations. Solving these problems interactively is essential and requires significant computation and graphics power. While graphics and computing hardware have made rapid strides in the last few years, the software available to researchers has not kept pace. This lack of software is underscored by the recent emergence of the graphics supercomputers, which combine minisupercomputer-class computational power with 3D graphics capabilities that support real-time, interactive display of scientific and engineering data.
W. Gentzsch

Transputer — A General Survey

Abstract
Transputer — one more exotic appearance within the nearly immeasurable range of microprocessors? You might ask such a question, faced with the multitude of different processor types. The following article will point out the Transputer’s unique position amongst microprocessors. Not just a few look at the Transputer as the European answer to new and old processor architectures pouring in mostly from USA and Japan. This is especially true since SGS-Thompson, which is an important leader in European technologies, has taken over control in Transputers and has entered the processor market with stimulating offensiveness.
Gerd Häußler, Markus Grüner

Transputers in Technical Applications

Abstract
Parallel processing is rapidly becoming the mainstream of new data processing developments, taking over from the sequential von Neumann type of computer. Transputer based systems demonstrate the practical feasibility of supercomputer performance integrated with worldwide standards. This is done by means of bus interfaces supporting parallel processing within existing systems, workstations like VAX, PC, PS/2, SUN, VME, MAC, etc. and by making available standard programming languages such as FORTRAN, C, etc.
Siegfried Streitz

Quantum Chemical Calculations on MIMD Type Computers

Abstract
MIMD parallel computers can be a promising alternative in those cases where application software exploits only a small portion of the maximum performance of vector computers. We compare MIMD systems with other parallel architectures and stress transputer networks pointing out the benefits of this concept. Two different software environments are discussed, MultiTool, a modified transputer development system (TDS) and the distributed operating system Helios. Both are used to implement direct SCF programs on a transputer network. Parallel processing is defined according to the farming concept, both on the program and on the subroutine level. In transputer networks with up to 17 nodes, a very good load balance could be achieved, demonstrating the good suitability of the MIMD-concept for SCF calculations.
U. Wedig, A. Burkhardt, H. G. v. Schnering

Parallelizing an SCF program on SUPRENUM

Abstract
This article describes how an existing serial SCF-Programm can be adpated to a parallel computer architecture with distributed memory like the SUPRENUM system. The SCF program, which should be adapted, can be considered as a traditionally coded Gaussian lobe program as far as the code structure is concerned. The intregral part of the program is massively vectorized.
A short overview of the SUPRENUM system describes the basic features of the hardware, programming environment, and the user interface.
Ulrich Meier, Reiner Vogelsang

Drug Design: A Combination of Experiment and Computational Chemistry

Abstract
A “Rational Drug Design” depends on the explicit formulation of a Stucture-Activity-Hypothesis which postulates directly a relation between specific molecular parameters and the biological activity of a series of drug molecules as measured in a particular biological/pharmacological assay. The molecular parameters used in these relations are usually structural dimensions (e.g. distance between functional groups defining a pharmacophor, or defining a fitting molecular shape), and electronic parameters (e.g. particular electron density distributions, location of HOMO/LUMO molecular orbitals, etc.).
H. P. Weber

Conformational Analysis of Peptides Using Molecular Dynamics

Abstract
Peptides, especially peptide hormones and neurotransmitters, play an important role in medicinal chemistry. The study of peptide conformations enables the medicinal chemist to understand the structure-function relationship in order to design compounds which mimic the peptide (peptide mimetics).
G. Barnickel, E. Merck

The Use of Supercomputers in Medicinal Chemistry Examples from Peptide and Protein Projects

Abstract
Three examples of the use of molecular modeling techniques in drug research are discussed. A model of the threedimensional structure of Neuropeptide Y (NPY) was built up and used as a template for the successful design of a smaller peptide of very similar biological action. In the case of the very flexible ANF (atrial natriuretic factor) a conformational analysis using molecular dynamics at elevated temperatures gave essential hints on the bioactive conformation. In the third example (Phospholipase A2) some aspects of the modeling of protein structures and the design of active site inhibitors are briefly discussed. Modeling studies in all these examples could be performed only because of the availability of supercomputers.
H. Köppen

Local Density Functional Calculations on Properties of Large Molecules

Abstract
The local density functional is a well tested way to calculate quantum mechanical properties of atoms, molecules and solids. The Dmol implementation of such calculations is briefly introduced. A short overview on applications is given. Summaries of systematic studies are shown to guide expectations on the performance of the approach. Some applications are shown to illustrate the present capability.
B. Delley

Density Functional Calculations with Simulated Annealing — New Perspectives for Molecular Calculations

Abstract
The structure of a molecule or solid can be determined by calculating the total energy of the system of ions and electrons for all geometries. We review the problems inherent in such calculations, and show that the combination of density functional calculations with molecular dynamics techniques addresses the main difficulties. The method is applied to structural determinations in sulphur clusters S n , where the ground state geometries are described very well. The method also gives interesting results in cases where there are structural changes involving large barriers (S 7 O), and small energy differences with energy barriers on a thermal scale (isomers of Se x S y ). As a final example, we discuss recent results on small phosphorus clusters, P n , n = 2, 8.
R. O. Jones, D. Hohl
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