Scale Software and Message Passing

We now reexamine message passing as it pertains to software development and the interface of application software and library software. Compiler-managed parallelism is not yet ready for prime time. This means that efficient parallel programs are usually coded by hand, typically using point-to-point message passing and simple collective communications. There are many problems associated with this approach. 

Some of these problems will be alleviated by the emerging messagepassing interface standard. MPI incorporates two critical concepts that have historically been lacking from widely used packages. These concepts are process groups and contexts. Process groups are useful for organizing com- 

We now consider the status of parallelized computer codes and algorithms for computation in quantum chemistry, molecular dynamics, and reaction dynamics. Our focus is on the migration to parallel hardware of the major production codes commonly used, both on workstations and on conventional supercomputers, within the chemistry community. 

Following a general overview, that summarizes the pioneering role of the LCAP project, o give accounts of work in quantum chemistry, molecular dynamics, and reaction dynamics. Each of these subsections is organized to review the development and current status of codes in the area and to provide an overview of work under way where serial implementations are migrating onto parallel architectures. 

New architectures with their associated programming models, such as Cray s T3D and the KSR2 machine from Kendall Square Research, seem likely to provide platforms that will aid the development of computational chemistry 

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