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Chapter 2 The Rietveld Method

The INP file and data for Chapter 2.10 example refinement can be 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;

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