[ Identification | Description | Input parameters | Output parameters | Links ]

The Single_crystal Component

Mosaic single crystal with multiple scattering vectors.

Identification

Description

Single crystal with mosaic. Delta-D/D option for finite-size effects.
Rectangular geometry. Multiple scattering and secondary extinction included.
The mosaic may EITHER be specified isotropic by setting the mosaic input
parameter, OR anisotropic by setting the mosaic_h, mosaic_v, and mosaic_n
parameters. Geometry is a box.
Crystal structure is specified with an ascii data file. Each line contains
4 or more numbers, separated by white spaces:

      h k l ... F2

The first three numbers are the (h,k,l) indices of the reciprocal lattice
point, and the last number is the value of the structure factor |F|**2, in
barns. The rest of the numbers are not used; the file is in the format
output by the Crystallographica program.
Lines begining by '#' are read as comments (ignored).

Example: Single_crystal(xwidth=0.01, yheight=0.01, zthick=0.01,
          delta_d_d=1e-4, mosaic = 5,
          ax = 3.8186, ay = 0, az = 0,
          bx = 0, by = 3.8843, bz = 0,
          cx = 0, cy = 0, cz = 11.6777,
          reflections="YBaCuO.lau")

Vanadium incoherent elastic scattering with multiple scattering
Single_crystal(xwidth=0.01, yheight=0.01, zthick=0.01,
          reflections="", absorbtion=5.08, incoherent=4.935,
          ax=3.0282, by=3.0282, cz=3.0282/2)

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
reflections string File name containing structure factors of reflections. Use empty ("") or NULL for incoherent scattering only  
xwidth m Width of crystal  
yheight m Height of crystal  
zthick m Thichness of crystal (no extinction simulated)  
delta_d_d 1 Lattice spacing variance, gaussian RMS 1e-4
mosaic arc minutes Crystal mosaic (isotropic), gaussian RMS -1
mosaic_h arc minutes Horizontal (rotation around Y) mosaic (anisotropic), gaussian RMS -1
mosaic_v arc minutes Vertical (rotation around Z) mosaic (anisotropic), gaussian RMS -1
mosaic_n arc minutes Out-of-plane (Rotation around X) mosaic (anisotropic), gaussian RMS -1
ax 3.8186
ay AA Coordinates of first unit cell vector 0
az 0
bx 0
by AA Coordinates of second unit cell vector 3.8843
bz 0
cx 0
cy AA Coordinates of third unit cell vector 0
cz 11.6777
p_transmit 1 Monte Carlo probability for neutrons to be transmitted without any scattering. Used to improve statistics from weak reflections -1
absorbtion barns Absorbtion cross-section per unit cell at 2200 m/s 0
incoherent barns Incoherent scattering cross-section per unit cell 0
aa deg . 0
bb deg unit cell angles alpha, beta and gamma. Then uses norms of vectors a,b and c as lattice parameters 0
cc deg . 0
order 1 limit multiple scattering up to given order (0: all, 1: first, 2: second, ...) 0

Output parameters

Name Unit Description Default
hkl_info structure Internal  

Links


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Oct 27 12:32:23 2006