h
[hkl_plane $hkl] …
Used by the OpenGL viewer to display hkl planes, see the CeO2.STR file in the “Rigid” directory. Here are some examples:
str…
hkl_plane 1 1 1
hkl_plane “2 -2 0”
[grs_interaction [from_N #] [to_N #] [no_self_interaction] $site_1 $site_2 qi # qj # N E]…
Defines a GRS interaction with a name of N between sites identified by $site_1 and $site_2. E represents the GRS interaction equation that can be a function of R, which returns the distance in Angstroms between two atoms; these distances are updated when dependent fractional atomic coordinates are modified. The name of the grs_interaction N can be used in equations and in particular penalty equations.
When either from_N or to_N are defined, the interactions between $site_1 and $site_2 are sorted by distance and only the interactions between the from_N and to_N are considered.
no_self_interaction prevents any interactions between equivalent positions of the same site. This is useful when a general position is used to describe a special position.
qi and qj corresponds to the valence charges used to calculate the Coulomb sum for the sites $site_1 and $site_2 respectively.
grs_interaction is typically used for applying electrostatic restraints in inorganic materials. The GRS_Interaction macro simplifies the use of grs_interaction.
[hat E [num_hats #] ]…
Defines the X-axis size of an impulse function that is convoluted into phase peaks. num_hats corresponds to the number of hats to be convoluted. num_hats is set to 1 by default. hat is used for example by the Slit_Width and Specimen_Tilt macros.
[hkl_Is]…
[lp_search !E]
[I_parameter_names_have_hkl $start_of_parameter_name]
[hkl_m_d_th2 # # # # # # I E]…
Defines a phase type that uses hkls for generating peak positions.
lp_search uses a new indexing algorithm that is independent of d-spacing extraction; lp-search-pbso4.inp demonstrates its use. lp_search minimizes on a new figure of merit function that gives a measure of correctness for a particular set of lattice parameters. More specifically the figure of merit function assigns parts of the diffraction pattern to peaks and then sums the absolute values of the products of the diffraction intensities multiplied by the distance to the peaks:
where the summation in ‘j’ is over the calculated Bragg positions 2q0 and the summation in ‘i’ is over part of the diffraction pattern such that (2q0, j-1 + 2q 0, j.)/2 < 2qi < (2q 0, j+1 + 2q0, j.)/2. The method avoids difficulties associated with extracting d-spacings from complex patterns comprising heavily overlapped lines; the primary difficulty being that of ascertaining the number of lines present.
I_parameter_names_have_hkl gives generated Intensity parameters a name starting with $start_of_parameter_name and ending with the corresponding hkl.
hkl_m_d_th2: The numbers after the keyword hkl_m_d_th2 define h k l m d and 2q values, where
h, k, l : Miller indices
m : multiplicity.
d and th2 : d and 2q values (not used by).
I : Peak intensity parameter before applying any scale_pks.
If no hkl_m_d_th2 keywords are defined then the hkls are generated using the space group; the generated hkl_m_d_th2 details are appended at the end of the space_group keyword on refinement termination. Intensity parameters are given an initial starting value of 1. If the Le Bail keyword is not defined then the intensity parameters are given the unique code of @ .
For example, the following input segment:
xdd quartz.xdd
…
hkl_Is
Hexagonal(4.91459, 5.40603)
space_group P_31_2_1
will generate the following OUT file:
xdd quartz.xdd
…
hkl_Is
Hexagonal(4.91459, 5.40603)
space_group P_31_2_1
load hkl_m_d_th2 I
{
1 0 0 6 4.25635 20.85324 @ 3147.83321
1 0 1 6 3.34470 26.62997 @ 8559.23955
1 0 -1 6 3.34470 26.62997 @ 8559.23955
…
}
The Create_hklm_d_Th2_Ip_file macro creates an hkl file listing from structures in the same format as the “load hkl_m_d_th2 I” as shown above. Even though the structure would have no sites, the weight_percent keyword can still be used; it will use whatever value is defined by cell_mass in order to calculate weight_percent.
[hkl_Is_from_hkl4]