Hr. Karfunkel et al., CONTINUOUS SIMILARITY MEASURE BETWEEN NONOVERLAPPING X-RAY-POWDER DIAGRAMS OF DIFFERENT CRYSTAL MODIFICATIONS, Journal of computational chemistry, 14(10), 1993, pp. 1125-1135
The problem of quantifying similarity between crystal structures is tr
ansformed into the problem of comparing the associated X-ray powder di
agrams. A smooth similarity measure between two powder diagrams, terme
d a ''fold,'' is defined. In contrast to conventional comparison metho
ds, the introduced method is still applicable when the peaks of the sp
ectra to be compared have no overlap. The main areas of application of
the method are the construction of a molecular crystal structure when
only the experimental powder diagram is available and the analysis of
possible crystal packings predicted on the basis of molecular informa
tion only. A suitable empirical parameterization of the fold has been
derived from a large set of experimental and force-field-generated cry
stals. The analysis of 1-he outcome of an ab initio packing of a flexi
ble molecule is given as an example. The algorithmic details of the me
thod are given as a FORTRAN 77 code. (C) 1993 by John Wiley & Sons, In
c.