Volume 41 (1993) Issue 3 Pages 424-429
A fully automatic procedure has been devised for crystal structure analysis by X-ray crystallography. Automatic decisions at each critical point of the analysis, at which user intervention used to be required, are provided based on empirical considerations. The new procedure, named FACE (Fully Automatic Struture Elucidation), simply refins the intense peaks using two-step weighted Fourier (WTF) calculations following phase determination. The molecular recognition based on the interpretation of electron-density maps is not necessary in this procesure. It is able to solve structures without any user intervention; the user simply inputs "FASE" to carry out this procedure. The complete structure is solved and displayed in most cases. This procedure has been applied to 137 crystals of organic compounds and 112 chemically significant structures were derived. The R values refined without any missing atom using isotropic refinement normally lie in the range of 0.15-0.30, which are acceptable values in such a rough stage (all non-hydrogen atoms are assigned as carbon). These results usually reached to the final structure, including hydrogen atoms with R values around 0.05, by further anisotropic refinement using appropriate methods.