A simple statistical residual has lead to further improvements in the method. The software has been highly optimized to achieve good performance of small and medium-sized problems. A library of protein fragments has been compiled by exhaustive analysis of the Protein DataBank. A collaboration has been undertaken with Lynn Ten Eyck of San Diego Supercomputer Center, to investigate the eigenvalues and eigenvectors of the refinement normal matrix. In the future it is possible that this work will suggest new parameterisations for the model and improved optimization algorithms.
Work continues on the development of methods for phase improvement by density modification.
Initial calculations have been performed to provide further information concerning theoretical aspects of this work. Future applications will increasingly have to combine all the information available in order to determine a crystal structure. This will require better tools for the storage, manipulation, and cross referencing of crystallographic data. These libraries may be employed on their own, or integrated with the CCP4 libraries, which are being updated in parallel. Once this work is completed, development of new applications, either using the libraries directly or through a scripting interface should be considerably quicker.