How do you do a coordinate system?
When we use coordinates to locate a point on a coordinate plane, we use two numbers to specify the horizontal (x) and vertical (y) positions.
The first number in a coordinate pair tells us how far to move left or right from the origin, while the second number tells us how far to move up or down..
What are crystallographic coordinates?
In crystallography, a fractional coordinate system (crystal coordinate system) is a coordinate system in which basis vectors used to the describe the space are the lattice vectors of a crystal (periodic) pattern..
What are the coordinates of a lattice?
Lattice coordinates are given by specifying the position of a point using a combination of lattice vectors.
Fractional components indicate a position inside the unit cell and could be used, for example, to specify the positions of the atoms in the crystal basis..
What are the coordinates of the unit cell?
These positions are defined by the coordinates: 0,0,0; 0,1/2,1/2; 1/2,0,1/2; and 1/2,1/2,0.
The presence of an particle at one corner of the unit cell (0,0,0) requires the presence of an equivalent particle on each of the eight corners of the unit cell..
What are the fractional coordinates of a crystal structure?
The atomic coordinates of a crystal structure are usually expressed as fractional coordinates, i.e. as fractions of the a, b and c unit cell vectors.
For example, an atom with fractional coordinates 0.5, 0.5, 0.5 would lie half-way along each unit cell edge, i.e. in the middle of the unit cell..
What are the three types of coordinates?
There are three commonly used coordinate systems: Cartesian, cylindrical and spherical.
In this chapter, we will describe a Cartesian coordinate system and a cylindrical coordinate system..
What is the coordinate system of crystals?
Fractional (crystal) coordinate system
In a fractional coordinate system the basis vectors of the coordinate system are chosen to be lattice vectors and the basis is then termed a crystallographic basis (or lattice basis).
However, the conventional basis for a crystal pattern is not always chosen to be primitive..
- The atomic coordinates of a crystal structure are usually expressed as fractional coordinates, i.e. as fractions of the a, b and c unit cell vectors.
For example, an atom with fractional coordinates 0.5, 0.5, 0.5 would lie half-way along each unit cell edge, i.e. in the middle of the unit cell. - These positions are defined by the coordinates: 0,0,0; 0,1/2,1/2; 1/2,0,1/2; and 1/2,1/2,0.
The presence of an particle at one corner of the unit cell (0,0,0) requires the presence of an equivalent particle on each of the eight corners of the unit cell.
