Jbt
–Structure factor model and refinement method for the phase
= 0 The phase is treated with the
Rietveld Method, then refining a given structural model.
= 1 The phase is treated with the
Rietveld Method and it is considered as pure magnetic.
Only magnetic atoms are required. In order to obtain
the correct values of the magnetic
moments the scale factor and structural parameters must
be constrained to have the
same values (except a multiplying factor defined by the
user) that their crystallographic
counterpart. See note on magnetic refinements. The
three extra parameters
characterising the atomic magnetic moments corresponds
to components (in Bohr
magnetons) along the crystallographic axes.
=-1 As 1 but the three extra parameters
characterising the atomic magnetic moments
corresponds to the value of M (in Bohr magnetons) the
spherical Φ angle with X axis
and the spherical Θ angle with Z axis. This mode works
only if the Z axis is
perpendicular to the XY plane. (for monoclinic space
groups the Laue Class 1 1 2/m is
required).
= 2 Profile Matching mode with constant
scale factor.
=-2 As 2 but instead of intensity the
modulus of the structure factor is given in the
CODFILn.hkl file
= 3 Profile Matching mode with constant
relative intensities for the current phase. The scale
factor can be refined. In this case Irf(n_pat) must be
equal to 2, see below.
=-3 As 3 but instead of intensity the
modulus of the structure factor in absolute units
(effective number of electrons for X-rays/ units of
10-12 cm for neutrons) is given in the
CODFILn.hkl file. This structure factor is given for
the non-centrosymmetric part of the
primitive cell, so for a centrosymmetric space group
with a centred lattice the structure factor to be read is:
Freduced =
Fconventional /(Nlat ⋅ Icen)
where Nlat is the multiplicity of the conventional cell
and Icen=1 for non-
centrosymmetric space groups and Icen=2 for
centrosymmetric space groups.
= 4 The intensities of nuclear
reflections are calculated from a routine handling Rigid body
groups.
= 5 The intensities of magnetic
reflections are calculated from a routine handling conical
magnetic structures in real space.
=+10/-10 The phase can contain nuclear
and magnetic contributions STFAC is called for
reflections with no propagation vector associated and
CALMAG is called for satellite
reflections. CALMAG is also called for fundamental
reflections if there is no
propagation vector given but the number of magnetic
symmetry matrices (MagMat, see
below) is greater than 0. The negative value indicates
spherical components for
magnetic parameters. For this case the atom parameters
are input in a slightly different
format.
=+15/-15 The phase is treated as a
commensurate modulated crystal structure. All the input
propagation vectors and also k=(0,0,0) are identified
to be magnetic and/or structural by
the reading subroutine. All nuclear contributions at
reflections without propagation
vectors (fundamental reflections of the basic
structure) and all the reflections associated
to a modulation propagation vector (superstructure
reflections), are calculated by
MOD_STFAC. Magnetic contributions are added, if
necessary, calling the subroutine
CALMAG as in the case of Jbt=+10/-10. The negative
value indicates spherical
components for magnetic parameters. This value of Jbt
implies the use of a specific
format for atom parameters.
Irf –Control the
reflexion generation or the use of a reflexion file
= 0 The list of reflections for this phase is automatically generated from
the space group
symbol
= 1 The list h, k , l, Mult is read from file CODFILn.hkl (where n is the
ordinal number of
the current phase)
=-1 The satellite reflections are generated automatically from the given
space group symbol
= 2 The list h, k, l, Mult, Intensity (or Structure Factor if Jbt=-3) is
read from file
CODFILn.hkl.
= 3 The list h, k, l, Mult, Freal, Fimag is read from file CODFILn.hkl. In
this case, the
structure factor read is added to that
calculated from the supplied atoms. This is useful
for simplifying the calculation of structure
factors for intercalated compounds (rigid host).
=4,-4 A list of integrated intensities is given as observations for the
current phase (In the case
of Cry≠0 this is mandatory)
Isy –Symmetry
operators reading control code
=0 The symmetry operators are generated automatically from the space group
symbol.
=+/-1 The symmetry operators are read below. In the case of a pure
magnetic phase Isy must
be always equal to 1 or 2.
=2 The basis functions of the irreducible representations of the
propagation vector group
are read instead of symmetry operators. At
present this works only for a pure magnetic
phase.
For Jbt=10 with magnetic contribution Isy could be 0 but a comment
starting with
“Mag” should be given after the space group symbol.
Str –
Size-strain reading control code
=0 If strain or/and size parameters are used, they are those corresponding
to selected
models
=1 The generalised formulation of strains parameters will be used for this
phase.
If Strain-Model≠0 a quartic form in reciprocal
space is used (see below)
=-1 Options 1 and 2 simultaneously. The size parameters of the quadratic
form are read
before the strain parameters.
=2 The generalised formulation of size parameters will be used for this
phase.
Quadratic form in reciprocal space. Only
special options of strains with Strain-
Model≠0 can be used together with this size
option.
=3 The generalised formulation of strain and size parameters will be used
for this phase.
Npr – Defaut profile to be used
Default value for selection of a normalised peak shape function.
Particular values can
for each phase, in that case the local value is used.
=0 Gaussian.
=1 Cauchy (Lorentzian).
=2 Modified 1 Lorentzian.
=3 Modified 2 Lorentzian.
=4 Tripled pseudo-Voigt.
=5 pseudo-Voigt.
=6 Pearson VII.
=7 Thompson-Cox-Hastings pseudo-Voigt convoluted with axial divergence
function (Finger, Cox & Jephcoat, J. Appl.
Cryst. 27, 892, 1994).
=8 Numerical profile given in CODFIL.shp or in GLOBAL.shp.
=9 T.O.F. Convolution pseudo-Voigt with back-to-back exponential
functions.
=10 T.O.F. Same as 9 but a different dependence of TOF versus d-spacing.
=11 Split pseudo-Voigt function.
=12 Pseudo-Voigt function convoluted with axial divergence asymmetry
function.
=13 T.O.F. Pseudo-Voigt function convoluted with Ikeda-Carpenter function.