Table 2. Parameters used in the numerical computations.

The dielectric susceptibilities are from Stepanov’s X-ray server (Stepanov, 2004 ▸). For the π polarization, we have included the \cos(2\Theta_{\rm B}) factor in the h component of the electric susceptibility. The crystal thicknesses are the mean values. The values in parentheses are the standard deviations of the variables assigned randomly in the Monte Carlo simulation

χ0 = −3.1745 × 10−6 + 1.6060 × 10−8 i
\chi_{h}^{\sigma} = 1.9210\times 10^{-6}-1.5497\times 10^{-8}i
\chi_{h}^{\pi} = (1.7899\times 10^{-6}-1.4345\times 10^{-8}i)\cos(2 \Theta_{\rm B})
λ = 0.0709317 nm	d220 = 192.014 pm
tS = 1.196 (2) mm	tA = 1.197 (2) mm
t1 = 1.193 (2) mm	t2 = 1.193 (2) mm
Δz = 0(4) µm	θ = 0(1) µrad
\Delta_{\rm e}^{\sigma} = 36.29 µm	\Delta_{\rm e}^{\pi} = 41.80 µm
μ0 = 1.423 × 10−3 µm−1	n0 − 1 = 1.587 × 10−6
κπ ≃ κσ ≃ π	νπ ≃ νσ ≃ −1