CPD News Index

CPD Chairman's Message

This is a busy time for the commission, the CPD is planning to increase its level of interaction and co- operation with other IUCr commissions, it will shortly endorse a set of guidelines on Rietveld refinement and will extend its coverage of powder diffraction into more applied areas. The field has moved on significantly in terms of software development. Groups from all over the world have been developing new ways to extract the maximum amount of information from powder profiles for structure solution and refinement. Maximum entropy, genetic algorithms, optimised direct methods and Monte Carlo techniques have all made recent advances and the fundamental parameters approach shows promise for Rietveld analysis. It is very difficult to know which of these approaches will be more fruitful so I asked Lachlan Cranswick if he would be prepared to solicit submissions of current powder structure solution and refinement developments on behalf of the CPD. I was expecting a small but significant response, what he obtained, as you can see, was an overwhelming response. That left a dilemma, publish shortened or the whole versions or the articles? I decided that in the interests of fairness we should publish all the information we received. This is not intended to be a comprehensive catalogue but it does show just how much work is being put into structure solution at present. We do not have all approaches represented, genetic algorithms and optimised direct methods are not discussed in detail. However Lachlan has assembled a great deal of information and I would like to thank him very much for his initiative. Our publication of this material does not endorse one approach over any other, it is intended to keep you informed about developments. We are fortunate that an increase in circulation and promised advertising revenue enables us to send out this extended issue without spending too much CPD funding. We would welcome informal submissions at any time from groups developing software and methods of potential interest to the powder diffraction community.

The next issue of the newsletter will be edited by professor Siba Sen Gupta, I would be grateful if you would send any information regarding events, developments or other activities directly to him. The next issue will cover powder diffraction in India and Asia and will contain details of the powder diffraction school in Calcutta this autumn.