cns2fsfour converts the CNS-style map into an XtalView FSFOUR-style map.

• i386 Linux ELF binary version 1.05
• IRIX6 (compiled on SGI IRIX 6.5) version 1.04
• SunOS5 binary version 1.04
• MacOSX PPC binary version 1.04
• MacOSX Mac Pro binary version 1.05
• Dec Alpha binary (compiled on OSF1 V4.0) version 1.03
• PC Linux ELF libc binary (kernel 2.0.35, compiled on Red Hat Linux 5.1) version 1.0
• Additional binaries should be available if you e-mail me.

The FSFOUR-style map describes an entire unit cell. Thus the crystal information (in the crystal file) needs to be specified if less than an entire unit cell is in the file. This can be done on the command line or by the appropriate environment variables as described below. (This usage mirrors XtalView usage, so it should be natural for XtalView users.)

FSFOUR maps are binary and XtalView doesn't properly handle bytes in the wrong byte order. Starting with cns2fsfour version 1.05, a -swapbytes command line argument will cause the program to write maps of opposite byte order for cases when maps need to be read by machines of different endianness (for example a Mac Pro generated map being read by a Mac PPC version of XtalView, which may be running on the same machine).

The search order for the crystal file is the current directory and then the directory pointed to by the the environment variable CRYSTALDATA (same as used in XtalView). The crystal file to be read is first taken from the command line, and if not specified there, from the CRYSTAL environment variable (same as used in XtalView).

The format for the crystal information file is fairly simple. An example should suffice:

name Test Crystal
cell 100.0 100.0 100.0   90.0 90.0 90.0
spgp p212121
symm  x,y,z; 1/2-x,-y,z+1/2; x+1/2,1/2-y,-z; -x,y+1/2,1/2-z.

When writing the CNS map, it is important to write out all of the unique information. The appropriate options to choose are either the entire unit cell or the asymmetric unit. The asymmetric unit option only works if you give cns2fsfour crystal information so it can do a symmetry expansion. Note that for the composite omit map script, the map extent must be edited manually as it is not an option on the web interface.

{* extent of map *}
{+ choice: "molecule" "asymmetric" "unit" "box" "fract" +}
{===>} map_mode="asymmetric";

You should also ensure that map is being written in the CNS format rather than the EZD format.

{* map format *}
{* choice: "cns" "ezd" *}
{===>} map_format="cns";

When reading in (any) FSFOUR maps into XtalView, right-click on the Load/write Map button under the Files... dialog and choose "Load Fsfour Format Map (*.map)". Simply choosing the default (reading the file as if it were a text phase file) won't work.

There are a few incompatibilities that need to be addressed in new versions that should make the conversion robust.

I had an older solution that used a script, cns2fsfour.com, to convert the CNS map to FSFOUR via CCP4. This required a number of programs to be available and somehow introduced some empty planes that I haven't yet traced. The current cns2fsfour program appears to be a superior solution than the script.

As always, I've only extensively tested this program against many of the things that I do regularly so there are potentially a number of bugs that are creeping about. I've written the program to be very robust so that it should survive even fairly pathological cases, but I've only checked a finite number of these. If you run into any problems, feel free to e-mail me and depending on the problem (and my schedule) I might crack open the code and fix them.

Praise and requests for options that would be useful are also welcome.