p2gg
First edition 06/ 8/ 2013, last update 24/ 11/ 2013
in English/ in Portuguese
The periodic plane distribution of a big disk connected to a couple
of small disks given in this page can be studied in crystallography with
4 correct and different possibilities. In each possibility the center of
the disks in general position will have different coordinates related to
the origin of the unit cell
Analyze with attention this data. You are invited to resolve the following
items.
-
Identify the correct symbol for the unit cell in the given periodic plane
distribution above.
-
Write the coordinates given by this application to define the origin of
each kind of unit cell.
-
Write the dimension of the unit cells found in 2.
-
Attribute coordinates x = 0 and y = 0 to the origin of each unit cell and
write the coordinates of the objects in general position and in special
position and the respective multiplicity.
-
Describe any relationship among the size of the disks and the kind of the
position in the unit cell, respectively for each possibility.
The Status bar will display the mouse coordinates after a mouse move action
on the figure. After a click on the right button of the mouse on any selected
point on the figure the origin, with x = 0 and y =0 will be true for that
point. Those are resources used in the program "oito2". Actually the tested
browsers "Internet Explorer 10" and "Safari 5.1.10" are suitable. Browsers
"Firefox 25.0", "Konqueror 4.10.5" and "Safari 5.1.7" are unable to display
the figure or unable to display the coordinates on the status bar or the
status bar shows wrong coordinates.
Reference
International Tables for Crystallography (2005). Vol. A, edited by T.
Hahn, Dordrecht: Springer.
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