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====== Chapter 2 The Rietveld Method ======
The INP file and data for Chapter 2.10 example refinement can be [[http://community.dur.ac.uk/john.evans/topas_book/2.10_Rietveld_example.zip|downloaded here]]
The INP file is:
'Chapter 2.10 example Rietveld
r_wp 7.34111042 r_exp 3.66232277 r_p 5.74261357 r_wp_dash 8.8207248 r_p_dash 7.03064237 r_exp_dash 4.4004707 weighted_Durbin_Watson 0.527830172 gof 2.00449575
xdd "RbBrMgBr2_6H2O_295K.raw" ' Powder pattern in Bruker raw format
'do_errors ' flag to calc. standard uncertainties
bkg @ 139.001787` 61.1515993` 10.7947705` 10.6608404` -11.6532545` 18.5000384` ' 6th-order background polynomial
One_on_X(@, 13417.42749`) ' 1/X background term
start_X 10 ' Start 2theta
lam ' Wavelength section
ymin_on_ymax 0.0001 ' Extent of peak width
la 1 lo 1.540596 lh 0.401844 ' rel.int.,lam, Lorentzian width of emission
Zero_Error(@, 0.00213`) ' Refined zero shift
LP_Factor( 27.3) ' Lorentz-polarisation factor for Ge(111)
Rp 217.5 ' Primary radius of the diffractometer
Rs 217.5 ' Secondary radius of the diffractometer
axial_conv ' Axial convolution section
filament_length 8 ' Length of the filament
sample_length 8 ' Length of the sample
receiving_slit_length 8 ' Length of the receiving slit
secondary_soller_angle @ 2.65566` ' Angle of the secondary Soller slit
axial_n_beta 20 ' Number of rays in the axial plane used to describe the axial aberration
Slit_Width( 0.1) ' Width of a strip of the PSD
prm muR 0.01792` min 0.01 max 1.0 ' Refined mueffR for absorption calculations
Cylindrical_I_Correction(muR) ' Intensity correction
Cylindrical_2Th_Correction(muR) ' Positional correction
str ' Tree level for the RbBr impurity phase
phase_name RbBr ' Phase name for the GUI
Strain_G(!stg, 0.17437) ' Fixed Gaussian microstrain broadening
r_bragg 2.95277685 ' Bragg-R-factor
MVW( 661.487, 327.428, 3.344`) ' Mol. mass of cell contents, cell volume, wt%
scale @ 3.35557378e-05` ' Scale factor
space_group Fm-3m ' Hermann Maguin space group symbol
Cubic( 6.89242) ' Fixed cubic lattice parameter
' Atomic site, label, Wyckoff mult., fract. coord., occupancy, displ. param.
site Rb2 num_posns 4 x=0; y=0; z=0; occ Rb+1 1 beq !B1 2
site Br3 num_posns 4 x=1/2; y=1/2; z=1/2; occ Br-1 1 beq =B1;
str ' Mg(H2O)6RbBr3 phase
phase_name Mg(H2O)6RbBr3
CS_L(@, 709.44256`) ' Lorentzian size broadening
CS_G(@, 8195.54867`_LIMIT_MIN_0.3) ' Gaussian size broadening
Strain_G(@, 0.12346`)
r_bragg 3.74108511
MVW( 1781.925, 1311.448`, 96.656`)
scale @ 8.99061654e-05`
space_group C12/c1
a @ 9.641804`
b @ 9.865797`
c @ 13.786729`
be @ 90.08759`
site Br1 num_posns 4 x=1/2; y=0; z=1/2; occ Br-1 1 beq B2 1.79041`
site Br2 num_posns 8 x @ 0.25268` y @ 0.74022` z @ 0.74821` occ Br-1 1 beq=B2;
site Mg1 num_posns 4 x=1/2; y=1/2; z=1/2; occ Mg+2 1 beq=B2;
site Rb1 num_posns 4 x=1/2; y @ -0.00425` z=3/4; occ Rb+1 1 beq=B2;
site O1 num_posns 8 x @ 0.40634` y @ 0.68311` z @ 0.53754` occ O-2 1 beq=B2;
site O2 num_posns 8 x @ 0.31834` y @ 0.39434` z @ 0.55055` occ O-2 1 beq=B2;
site O3 num_posns 8 x @ 0.41373` y @ 0.51740` z @ 0.36101` occ O-2 1 beq=B2;