SYMCONV is a utility program that allows interrogation of the CCP4 symmetry library. It provides a way to look up spacegroup information (SPACEGROUP keyword), and to acquire data about symmetry operations expressed in different formats.
There are no input or output files associated with SYMCONV; all input is via keywords and all output is to standard out.
The program is designed to be able to operate in an interactive manner, so the order that keywords are supplied are important - the output of later commands e.g. OP will be affected by commands entered previously in that run.
The available keywords are:
OP, XDS, NOXDS, CELL, NOCELL, RCSB, NORCSB, SPACEGROUP, NOSPACEGROUP, END
The OP keyword must be followed by a symmetry operation expressed in string format, e.g. x,y,z or x-y,x,z+1/2 (real space) or h,-l,k (reciprocal space).
The program will print the equivalent symmetry matrix, and for reciprocal space operations it will also print the XDS REIDX command. If a cell has previously been supplied via the CELL keyword then the symmetry operation matrix to be applied to real space atom coordinates will also be printed. If a spacegroup has previously been supplied via the spacegroup command then the program will identify the sym.id for the operation, plus any additional lattice translations that may have been applied (for real space operations only). If the RCSB symmetry data is available then it will also print the RCSB sym.id (see the RCSB keyword).
Specifying the XDS keyword means that an XDS REIDX line will also be written out as part of the output of an OP keyword, when a reciprocal space symmetry operation is supplied. This is the default, and can be turned off using the NOXDS keyword.
Turn off the output of an XDS REIDX line by the OP keyword. Turn back on using the XDS keyword.
Specify a unit cell to be used in conjunction with OP keywords. Cell lengths are in Angstroms and cell angles are in degrees; if the angles are not specified then they default to 90 degrees.
After a CELL keyword is given the program will generate and print the fractionalising and orthogonalising matrices. It will also store the cell parameters and use them for subsequent OP keywords, to generate the real space symmetry matrix. Use the NOCELL keyword to clear the cell parameters.
Clear the unit cell parameters specified by a previous CELL keyword.
Turn on the printing of the RCSB sym.ids for SPACEGROUP and OP keywords (this is the default).
Use the NORCSB keyword to turn off this behaviour.
Turn off printing of the RCSB sym.ids (see the RCSB keyword).
Look up a spacegroup in the syminfo.lib file and return information such as number and a list of symmetry operations and sym.ids (sym.id is the position of the operator in the list).
After a SPACEGROUP keyword is given the program will also store the spacegroup information (if the spacegroup was found in the library), and will attempt to look up symmetry operations given by subsequent OP keywords. If the symmetry operation is found in the list of operators for the current spacegroup then its sym.id is reported. Use the NOSPACEGROUP keyword to clear the spacegroup information.
Clear the spacegroup data specified by a previous SPACEGROUP keyword.
End of input, also end-of-file will do.
Due to a bug in the CCP4 parser library in releases 6.0.1 and earlier, the RCSB lookup functions may not work correctly. This has been fixed for subsequent CCP4 versions (6.0.2 and later).
Peter Briggs, CCLRC Daresbury Laboratory
August 2006
The program also includes spacegroup data kindly provided by the RCSB-PDB.