# # Model function for Reflectivity evaluation # mu = 1.130469005513490E-001 # (cm-1) @ 17.479 keV t0 = 0.18 # cm tb = 11.417823202820120 * 0.01745329251994 # thetaB (radians) A = mu * t0 / cos(tb) P = (1 + (cos(2.*tb))**2) / 2 Fhkl = sqrt(3.536346308456155**2 + (4.58815426260982e-4)**2) * 0.968 r0 = 2.81794092e-13 # classical electron radius lambda = 7.09338062818239e-9 # Mo K in cm V = 1.62253546981499e-23 P = (1. + (cos(2.*tb))**2) / 2. # # combine constants to avoid exponential overflow on systems with # D floating point format where exponential limits are ca. 10**(+/-38) # r0liV = r0 * lambda / V r0liV = 2.81794092*7.09338062818239/1.62253546981499e-1 # W(x) = 1./(sqrt(2.*pi)*eta) * exp( -1. * x**2 / (2.*eta**2) ) Y(tc) = tc/sin(tb) * Fhkl * r0liV f(tc)= (tanh(Y(tc)) + abs(cos(2.*tb)) * tanh(abs(Y(tc)*cos(2.*tb)))) / (Y(tc)*(1.+(cos(2.*tb))**2)) Q(tc) = (r0*Fhkl/V)**2 * (lambda**3/sin(2.*tb)) * P * f(tc) a(x) = W(x) * Q(tc) / mu # R(x) = sinh(A*a(x)) * exp(-1.*A*(1.+a(x)))