Scope of Parallelism and Integration with main Castep Codebase

The current implementation of band-parallelism has been restricted to the groundstate calculation. Geometry optimisation and molecular dynamics calculations have not been tested, but it should be trivial to get them to work if they do not already. However EDFT with conduction bands, real space representations of $\beta$-projectors, and band-structure calculations all currently use an older, obsolete subroutine to obtain their eigenstates and this has not been parallelised over bands. The reason for this omission is simply that the correct course of action is to change these code paths to use the newer subroutine instead, which is already parallelised over bands.

The band-parallel version of Castep writes a standard Castep checkpoint file, so users wishing to perform operations that are not supported in band-parallel mode can still benefit from the band-parallel code by using it for their groundstate calculation, and then continuing their calculation with a normal Castep run.

An alpha-release of the band-parallel code was made to selected collaborators in June 2008. The aim is to integrate the band-parallelism and the main Castep code base for Castep release 4.4. This release is due in the last quarter of 2008, and will open up the band-parallelism to the whole Castep community. In addition to the groundstate calculations, geometry optimisations and molecular dynamics will be supported, as will EDFT. It is hoped that band-structure calculations and the use of real space $\beta$-projectors will also be supported, but depending on time this may need to wait until version 4.5.