y = sf_hard_spheres(p, x, [y]) : Hard Sphere structure factor [Percus-Yevick]
iFunc/sf_hard_spheres Hard Sphere structure factor, suited for simple liquids
The 'x' wave-vector/momentum axis is usually in nm-1 or Angs-1.
The parameter RHS is given in inverse unit of the axis (that is nm or Angs).
Typical values for parameters are R=3-50 Angs, rho=0.2.
The Hard Sphere model corresponds with the Sticky Hard Sphere model with large tau.
The model returns the S(q) structure factor.
Ref: J. K. Percus and G. J. Yevick., Phys. Rev., 110(1):1–13, 1958.
A. Vrij., J. Chem. Phys., 71(8):3267–3270, 1979.
Extracted from sasfit/sasfit_sq/sasfit_sq_HardSphere.c
I. Bressler, et al, Journal of Applied Crystallography, 2015, 48 (5), 1587-1598
input: p: hard sphere model parameters (double)
p = [ R=Hard_Sphere_Radius rho=Volume_Fraction ]
or 'guess'
x: wave-vector/momentum axis (double, e.g. nm-1 or Angs-1)
y: when values are given and p='guess', a guess of the parameters is performed (double)
output: y: model value (intensity)
ex: y=sf_hard_spheres([10 0.2], 0:0.01:1); or plot(sf_hard_spheres,[10 0.1],0:0.01:1)
Version: Aug. 22, 2017
See also iFunc, iFunc/fits, iFunc/plot
(c) E.Farhi, ILL. License: EUPL.