Using the supplied NaCl basis and model amplitudes, calculate F111, F200 and I*111/I*200. Repeat the ratio after setting both species' amplitudes to1 without moving any atom. Explain what this comparison demonstrates about geometry and chemical scattering contrast.

Use the supplied periodic conventional cubic cell, not an isolated XYZ cluster. Cartesian XYZ coordinates are in angstrom; 1 nm=10 angstrom. XYZ atom rows start at one after the two header lines. Fractional positions below are exact; each listed basis atom has occupancy 1. Cell vectors are (a,0,0),(0,a,0),(0,0,a); all angles90 degrees. Crystal images are r_j+a*(n_x,n_y,n_z) for integer n. No relaxation, defects, thermal motion or finite crystallite envelope is supplied.
halite S0008: a=5.64056 angstrom. Row / element / fractional x,y,z:
1 Na 0 0 0
2 Na 0 1/2 1/2
3 Na 1/2 0 1/2
4 Na 1/2 1/2 0
5 Cl 0 0 1/2
6 Cl 0 1/2 0
7 Cl 1/2 0 0
8 Cl 1/2 1/2 1/2

Use fractional coordinates x_j,y_j,z_j from the table and F(hkl)=sum_j f_j exp[2*pi*i*(h*x_j+k*y_j+l*z_j)], where i^2=-1. All occupancies are1. Define I*=|F|^2. This is only the basis structure-factor contribution, not a measured powder peak intensity; omit multiplicity, Lorentz/polarization, thermal and absorption corrections. In case A use real constants f_Na=11 and f_Cl=17. These are explicitly illustrative model weights, not measured ionic X-ray form factors and not a particular experimental scattering angle. In case B use f_Na=f_Cl=1. Keep coordinates, origin and positive phase convention unchanged. Report each complex F and the intensity ratios to six decimals.

Attachment S0008:
8
Coordinates in angstrom; atoms numbered from 1.
Na 0.00000000 0.00000000 0.00000000
Na 0.00000000 2.82028000 2.82028000
Na 2.82028000 0.00000000 2.82028000
Na 2.82028000 2.82028000 0.00000000
Cl 0.00000000 0.00000000 2.82028000
Cl 0.00000000 2.82028000 0.00000000
Cl 2.82028000 0.00000000 0.00000000
Cl 2.82028000 2.82028000 2.82028000