Dear Liang, Might I suggest that you use ASCII characters for your name, otherwise the characters appear meaningless to most email readers. For example, your name appears as ½¨²¨Áº Why not instead write "Liang Jian Bo" ?
Automatic indexing of powder patterns requires very precise measurement of line-spacings and in particular special efforts to eliminate zero error. Indexing programs can suggest cells that do not index all lines; they try to calculate the probability of the cell being correct by looking at the match to the first 20 lines. If several of these are not matched, and the cell has low symmetry, it is unlikely to be correct. More effort to obtain a pure sample and reduce measurement error will be more effective than further computation. To answer your question, the indexing program will itself report the cell dimensions and angles of any matching monoclinic cells. You might then try a Pawley (sometimes called le Bail) refinement of the cell parameters, and use a crystal structure database such as ICSD or COD to search for similar compounds with hopefully similar cell dimensions. Finally, you can only be reasonably confident that you have identified the material if you obtain a good Rietveld fit for the structure i.e. a model that fits the line intensities as well as the line spacings. Best wishes, Alan. ½¨²¨Áº said: > Could anyone give some advices how to determine cell parameters of a > monoclinic phase, especially, the angles. ______________________________________________ Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE <alan.he...@neutronoptics.com> +33.476.98.41.68 http://www.NeutronOptics.com/hewat ______________________________________________