Journal of Applied Crystallography

Volume 30, Part 1 (February 1997)

computer programs

J. Appl. Cryst. (1997). 30, 73-78 [ doi:10.1107/S0021889896006711 ]

A computer program to derive (3+1)-dimensional symmetry operations from two-line symbols

Z.-Q. Fu and H.-F. Fan

Abstract: A computer program has been written for the derivation of (3 + 1)-dimensional symmetry operations from the two-line symbols. The derivation is based on the concept of generators {[(R^v_E), ^v, s^v, ^v, q)|v = 1, NG}, in which {[(R^v_E), s^v)|v = 1, NG} denotes the set of generators of the basic space group represented by the upper line. The program, called SPGR4D, is written in Fortran77 and based on the program by Burzlaff & Hountas (1982). [J. Appl. Cryst. (1982), 15, 464-467] for the derivation of symmetry operations in three-dimensional space. SPGR4D has been incorporated into a new version of the direct-methods program DIMS for solving incommensurate modulated crystal structures.