Computers in Physics
Volume 5, Issue 3, May 1991
Index of content:
- PEER-REVIEWED PAPERS
5(1991); http://dx.doi.org/10.1063/1.168420View Description Hide Description
A molecular dynamics algorithm for performing large‐scale simulations on the Connection Machine, a massively parallel supercomputer, is discussed. The algorithm uses a cell data structure to obtain the near neighbors of each particle as the fluid evolves. The main features of the data structure are that one processor per particle is used to integrate the equations of motion of each particle and one processor per cell is assigned to compute the interparticle forces. The results for Lennard‐Jones fluids of 15 000 to 500 000 particles indicate that the algorithm scales linearly with the number of particles.
Computing Dirac’s atomic hydrogen wave functions of the continuum, using summation of mathematically divergent series5(1991); http://dx.doi.org/10.1063/1.168410View Description Hide Description
Accurate computation of the positive and negative energy wave functions for the continuous parts of the atomic hydrogen spectrum, at large distances from the proton, provides an example of the problems in which sums of mathematically divergent series have to be computed. Here it is shown how such summations can be performed and what checks on the accuracy of the methods are used. Similar methods should be applicable in many other cases.
5(1991); http://dx.doi.org/10.1063/1.168411View Description Hide Description
A programmable interface system, designed for general use in the laboratory, is described. The system is designed to be used as a peripheral on the IEEE‐488 Instrumentation Bus and features an interactive Forth interpreter that allows for considerable flexibility in its applications. The system simplifies both hardware and software problems commonly encountered, in the design of data acquisition and control systems and makes them less dependent on specific features of the controlling computer. The interface system provides simple electrical connections that can be adapted to suit a wide range of instruments, and, through programming, the functionality of an interface system and its associated instruments can be tailored to particular situations. Several interface systems can operate simultaneously on the same bus, in which case a number of data acquisition or control tasks can be executed in parallel, each on a separate interface system CPU. The software implementation of the system is described in detail.