# XTal605

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1. What is a Lattice Point
A point in the lattice.  "Any point with identical surrounding as a given reference point".
2. What is a lattice
Empty periodic pattern
3. What is a Lattice Vector
base at origin to a lattice point
4. What is a Basis Vector
the lattice vectors that form the unit cell
5. List the axis systems
• - Cubic: a=b=c, all angles 90
• - hexagonal: a=b not c, two angles 90, one 120
• - tetragonal: a=b not c, all angles 90
• - orthorhombic: a not b not c, all angles 90
• - trigonal: a=b=c, all angles equal, less than 120 not equal to 90
• - monoclinic: no sides equal, all angles 90
• - triclinic: no sides equal, no angle equal
6. List the Bravais Lattices
• Cubic: Primitive (P), body centered (I), face centered (F)
• Tetragonal: Primitive (P), body centered (I)
• Orthorhombic: Primitive (P), Single face centered (C), body centered (I), all face centered(F)
• Monoclinic: Primitive (P), single face centered (I)
• triclinic: Primitive (P)
• trigonal: Primitive (P)
• hexagonal: primitive (P)
7. What is the Structure Matrix
used to transform lattice vector to cartesian vector
8. What is a Metric Tensor
Tensor used to determine dot product of lattice vectors (the dot product must be evaluated in cartesian coordinates).
9. What is symmetry
the spatial relationship between identical objects in patterns
10. What is a Symmetry Operation
produces an image object from an original object where both the original and image objects are congruent (all distances and angles remain the same).
11. List the Symmetry Operations
• inversion -
• Translation
• rotation - n
• reflection - m (or 1/m for mirror planes perpendicular to rotation axis)
• roto-inversion -
• glide - am/m
• screw - nk
12. List the Symmetry Elements
• translation vector
• rotation axis
• mirror plane
• inversion center
• roto-inversion axis
• glide plane
• screw axis
13. What is a Symmetry Element
an imaginary object that performs a symmetry operation
14. What is the Multiplicity of a symmetry operation
the number of repetitions required to produce an image identical (not just congruent) to the original
15. What is a Chiral Object
the image of an original object formed by reflection or inversion
16. What are Generating Elements
the symmetry elements that can be combined to generate a point group (sometimes bycreating new symmetry elements)
17. Hermann-Mauguin symbols
• 1-triclinic, C1,order 1
• -triclinic, C1,order 2
• 2 -monoclinic, C2, order 2
• m-monoclinic, Cs, order 2
• 2/m- monoclinic, C2h, order 4
• 222- orthorhombic, D2, order 4
• 2mm- orthorhombic, C2v, order 4
• mmm- orthorhombic, D2h, order 8
• 4 -tetragonal, C4, order 4
•  - tetragonal, S4, order 8
• 4/m- tetragonal, C4h, order 8
• 422- tetragonal, D4, order 8
• 4mm- tetragonal, C4v, order 8
•  - tetragonal,D2d, order 8
• 4/mmm - tetragonal, D4h, order 16
• 3 - trigonal,C3, order 3
•  - trigonal, C3i, order 6
• 32 - trigonal, D3, order 6
• 3m - trigonal, C3v, order 6
•  - trigonal,D3d, order 12
• 6 - hexagonal, C6, order 6
•  - hexagonal, C3h, order 6
• 6/m - hexagonal, C6h, order 12
• 622 - hexagonal, D6, order 12
• 6 m m - hexagonal, C6v, order 12
•  - hexagonal,D3h, order 12
• 6/m mm - hexagonal,D6h, order 24
• 23 - cubic,T, order 12
•  - cubic, Th, order 24
• 432 - cubic, O, order 24
•  - cubic, Td, order 24
•  - cubic, Oh, order 48
18. Identify Hermann-Maugiun - 1st digit 1
Triclinic
19. Identify Hermann-Maugiun - 1st digit 2 or m
monoclinic
20. Identify Hermann-Maugiun - 3 digits (2 or m)
orthorhombic
21. Identify Hermann-Maugiun - 1st digit 4
tetragonal
22. Identify Hermann-Maugiun - 1st digit 3
trigonal
23. Identify Hermann-Maugiun - 1st digit 6
hexagonal
24. Identify Hermann-Maugiun - 2nd digit 3
cubic
 Author: cdweasel ID: 172048 Card Set: XTal605 Updated: 2012-09-20 02:55:08 Tags: Crystallography Folders: Description: Crystallgraphy terms Show Answers: