HKL Shifts Parameters Refinement Dialog

 

 

 

HKL-dependent shift parameters [SHF1, SHF2, SHF3]

These parameters are defined by the user through the subroutines SHIFHKL, where a particular model for displacement of Bragg reflections is built for each model.

 

Shift Axis vector [Sh1, Sh2, Sh3]

Is the vector defining the “shift axis”. Should be the same for all patterns. The position of the reflection is displaced according to the expressions:

(ISHIF=1)

                                                                        

 

(ISHIF=-1)

                                                                        

 

where  is the angle between the reciprocal vector  and the direct vector .

 

 

Rules for shifts on Bragg positions

 

 

 

Defining rules (max. 10) to be satisfied by reflections undergoing shifts with respect to the theoretical Bragg position, due to some kind of defects: stacking and twin faults.

Are set of integers that should be the same for all patterns. If the Miller indices of the reflection satisfy the relation:

 

                                                               

 

The position of the reflection is displaced according to the expressions:

 

2Theta:

                                                             

 

T.O.F.:

                                                            

 

Energy:

                                                               

 

 

General shift formulation

 

 

In the case that Generalized shift ( , with N=2,4), then the position of the reflection is displaced according to the expressions:

 

2Theta:

                                                               

 

T.O.F.:

                                                              

 

Energy:

                                                                 

 

The expression used for calculating the scalar  for reflection  is given by:

 

 

 

according with the Laue class selected.

 

Laue class: -1

D2_200, D2_020,    D2_002,        D2_011,        D2_101,        D2_110

D4_400, D4_040,    D4_004,        D4_220,        D4_202

D4_022, D4_211,    D4_121,        D4_112,        D4_301

D4_301, D4_130,    D4_103,        D4_013,        D4_031

 

Laue class:  1 2/m 1

D2_200, D2_020,    D2_002,        D2_101

D4_400, D4_040,    D4_004,        D4_220,        D4_202

D4_022, D4_121,    D4_301,        D4_103

 

Laue class:  1 1 2/m

D2_200, D2_020,    D2_002,        D2_110

D4_400, D4_040,    D4_004,        D4_220,        D4_202

D4_022, D4_112,    D4_310,        D4_130

 

Laue class:  mmm

D2_200, D2_020,    D2_002

D4_400, D4_040,    D4_004,        D4_220,        D4_202,        D4_022

 

Laue classes: 4/m, 4/mmm

D2_200, D2_002

D4_400, D4_004,    D4_220,        D4_202

 

Laue classes: -3 R-3m R

D2_200, D2_002

D4_400, D4_004,    D4_112,        D4_211

 

Laue classes: -3 H, -3m1, -31m, 6/m, 6/mmm

D2_200, D2_002

D4_400, D4_004,    D4_112

 

Laue classes: m3, m3m

D2_200

D4_400, D4_220

 

 

 

Colour notes