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.
 

  1. Identify the correct symbol for the unit cell in the given periodic plane distribution above.
  2. Write the coordinates given by this application to define the origin of each kind of unit cell.
  3. Write the dimension of the unit cells found in 2.
  4. 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.
  5. 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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Table of subjects.
Presentation
Chemistry Analytical Chromatography
Elemental organic analysis
Volumetric analysis, simulation
Crystallography 3 fold screw axis
4 fold inversion axis on tetrahedron
5 fold rotation axis absent in crystallography
c2mm
c2mm unit cell origin hunter
Binary axis and reflection plane in stereographic projection
Bravais lattices
Conic sections under symmetry operators
Converting from spherical coordinates to stereographic projection
Crystal lattice and unit cell
Determination of unit cell
Elements of symmetry in action - animation
Elements of symmetry in action - cube game
Elements of symmetry in action - dodecahedron game
Elements of symmetry in action - icosahedron game
Elements of symmetry in action - octahedron game
Elements of symmetry in action - tetrahedron game
Ewald sphere and crystal measurements
Extinctions
Five classes in the cubic system
Five classes in the rhombohedral system
From tetrahedron to prism
Gnomonic projection
Improper symmetry axis
Miller indices
Miller indices - animation
Miller indices - cube game
Miller indices - octahedron game
Miller indices - rhombic dodecahedron game
Miller indices - tetrahedron game
Mirror plane
Mirror planes and Miller indices game - tetrahedron
Orientations of the cube
p2gg
p2mm
Plane symmetry groups
Question on point group
Rotation axis in octahedron and Werner compounds
Rotation axis on tetrahedron and organic molecules
Rotation of objects about an arbitrary axis
Rotation of the parallel and stereographic projections of the cube
Rotation of the stereographic and parallel projection of the cube III
Seven faces in stereographic projection
Seven classes in the hexagonal system
Seven classes in the tetragonal system
Six elements of symmetry in seven orientations
Spherical projection of the octahedron
Stereographic projection
Stereographic projection of six polyhedra in different orientations
Straight line equations and symmetry elements
Symmetry, 2 fold axis
Symmetry, 2, 3 and 6 fold axis in benzene
Symmetry, 3 fold axis in the cube
Symmetry, 4 fold axis in the cube
Symmetry, 4 fold axis in the unit cell of gold
Symmetry elements and Miller indices game
Symmetry elements and Miller indices game - octahedron
Symmetry in art and in crystallography
Three classes in the monoclinic system
Three classes in the orthorhombic system
Twin crystals
Two classes in the triclinic system
Unit cell in hexagonal net
General Butane conformations
Density
Electrochemical cell
Ethane conformations
Oxidation and reduction
Resources of chemical-ICT: water, health and symmetry
Solid and liquid gold