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--- chapter_2_-_the_rietveld_method [2018/11/23 11:16] – created johnsoevans
+++ chapter_2_-_the_rietveld_method [2025/09/19 15:18] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Chapter 2 The Rietveld Method ======
+The INP file and data for Chapter 2.10 example refinement is linked here: {{ :2.10_Rietveld_example.zip |}}
+The INP file is:
+<code topas>
+'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;
+</code>