Web tools enable Xtal to read and model CIF data automatically
Because the Xtal routine CIFIO can read and write files in CIF format,
it is simple to generate CIFs for
publication, or read and validate CIFs from other sources such as
the CSD. This is important for communicating data between the
increasing number of software packages, databases and journals that
receive and supply data in CIF format. It is possible to use a Tcl/Tk
script to link the Xtal System or RasMol to CIFs downloaded
from databases or journals using the web browser Netscape
The steps in this process are illustrated below.
Xtal can be used to view CIF's downloaded by
Netscape via Tcl/Tk filter as a helper application.
When this filter is installed, clicking on the [CIF] URL in the
left-hand corner of this Netscape display of a Acta C Contents
page, will download the CIF of the shown structure. This process
automatically opens up the CIF Filter window shown in the next
Clicking on the [Goto] button gives a menu of all of the
datablock header names in the CIF, and dragging to any of these
names moves the view pointer to the start of the datablock. For
example, in the left hand window the data block "re2biphoac4" is
highlighted in red.
Clicking on [data_re2biphoac4] invokes a popup menu permitting you
to choose the desired viewing software to visualize the structural
data stored in the "re2biphoac4" data block.
Selecting the [Xtal +tcl/tk] option brings up the Tcl/Tk XTAL
Program Control Window. The adjacent image shows the default Xtal
input control lines (top frame) and the output listing (bottom
frame) of executed programs. Control lines can be executed
individually or together. In this way graphics programs such as PIG
and PREVUE can be run and used to display the structural model
specified in the downloaded CIF.