The incentive to produce the Patterson Peaks tables is the continuing use of the Patterson method in determining crystal structures. Even though a variety of powerful direct methods have now been developed and coded into computer programs, the 60-year-old "F2-series" method [see, for example: A. L. Patterson, Phys. Rev. (1934). 46, 372-376; A. L. Patterson, Z. Krist. (1935). (A)90, 517-542] has strengths and features which complement those of direct methods and which encourage its use today.

The Patterson Peaks tables are intended to provide the positions and multiplicities expected for peaks in Patterson maps, assuming atoms to be in the general positions or in the special positions or in every possible combination of two independent sets of positions for all space groups and all origin and axis choices included in Volume A of International Tables for Crystallography (1995). The listed peaks are those which constitute a unique set in the Patterson map for each space group.

The computer program used to prepare the Patterson Peaks tables was adapted from part of Allan Zalkin's FORDAP Fourier program [Lawrence Berkeley Laboratory, Berkeley, CA 94720. Personal communication, June, 1974.]. The space group symmetry file used was based on the Enraf-Nonius MolEN SPACE.ASC file [C. Kay Fair. Personal communication, July 1989.] and was corrected and extensively augmented [increased in size by a factor of four!] to include the special positions and the unit cell origin description for each space group.

The Patterson Peaks tables follow the definitions, the page layout, and the fonts used for the space group tables in Volume A of International Tables for Crystallography [with permission from the International Union of Crystallography, personal communication from Philip Coppens, August, 1994] for all information taken therefrom to aid the reader in recognizing the information and to acknowledge its source. The Patterson peaks coordinates, consistent with their being vector quantities, are printed in italics [as recommended by Theo Hahn to Philip Coppens, July 1994]. The Patterson peaks multiplicities are printed in bold face.

The On-Line Brief Teaching Edition of Patterson Peaks is patterned after the Brief Teaching Edition of Volume A of International Tables for Crystallography and includes tables for the same set of space groups and origin and axis choices. It is hoped that all who use these tables would report any errors, omissions, or other problems found in any part of this publication and would also make suggestions to improve the content and the presentation.

Thank you.

Donald L. Ward
June 4, 1997
East Lansing, MI