Multiple rotation function.

A simultaneous analysis of several rotation functions allows identification of the model orientation in situations when a single rotation function fails to find the answer. Multiple rotation functions can be obtained by the usual modification of the search model or by variation of the resolution at which the function is calculated. A specially suitable case is a search with several NMR models. When the orientation of the model becomes available, its position can be found much more easily; low-resolution data can help in such a search. Many difficult cases of molecular replacement can be solved by new tools discussed in the article.