farfield_inputstructure matlab

Structural parameters

structrural parameters can be specified as follows

Unit cell and symmetry information

The unit cell parameters are given as follows

cell = [7.6944 9.7457 9.5827 90.000 90.000 90.000];

The space group number has to given, e.g. sgno = 64 for the space group Cmca
General systematic absent reflections for the space group are read automatically. But if extra systematic absences are present due to atoms located on positions with site symmetry. The specific systematic absences can be input by the user. For the space group Cmca it can look like this

sysconditions = [2 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2 0 0 0 0 0 0]

sysconditions(i) = X according to the scheme below

  i         class        systematic conditition
  1         HKL          H+K=XN
  2                      H+L=XN
  3                      K+L=XN
  4                      H+K,H+L,K+L = XN
  5                      H+K+L=XN
  6                      -H+K+L=XN
  7         HHL          H=XN
  8                      L=XN
  9                      H+L=XN
 10                      2H+L=XN
 11         0KL          K=XN
 12                      L=XN
 13                      K+L=XN
 14         H0L          H=XN
 15                      L=XN
 16                      H+L=XN
 17         HK0          H=XN
 18                      K=XN
 19                      H+K=XN
 20         HH0          H=XN
 21         H00          H=XN
 22         0K0          K=XN
 23         00L          L=XN

edit?]#Structural_parameters?

Structural parameters

The position and displacement parameters of the atoms in the asymmetric part of the unit cell are input as a Matlab structure with the structure name atomparam. One for atomparam for each atom. e.g.

atomparam(1).name = 'F';
atomparam(1).atomno = 9;
atomparam(1).pos = [0.30598 0.38512 0.07922];
atomparam(1).adp = [0.01455 0.02050 0.02320 0.00347 -0.00286 0.00464];
atomparam(1).occ = 1;
atomparam(1).symmulti = 1;

atomparam(2).name = 'N';
atomparam(2).atomno = 7;
atomparam(2).pos = [0.00000 0.15951 0.22929];
atomparam(2).adp = [0.0354 0.01624 0.01955 0.00592 0.000 0.000];
atomparam(2).occ = 1;
atomparam(2).symmulti = 2;

The parameter atomparam(1).symmulti is optional, as it can be calculated by simul_farfield. atomparam(1).symmulti is defined as "number of symmetry operations in the space group"/"Multiplicity of the site given in the Int. Tables. Vol. A"
The keyword symmulti can be used to control whether user assignment or calculation of atomparam(1).symmulti is wanted. symmulti can take these values

symmulti = 'all_one';   % The multiplicity for all atoms is set to 1.0 - i.e. it is known that
                        % all atoms are located on a general position
symmulti = 'calc';      % The multiplicity is calculated by simul_farfield
symmulti = 'input';     % The multiplicity is given by the user as seen in the above example