subroutine gelfit * SHIBAYAMA-GEISSLER TWO-LENGTH SCALE SCATTERING FUNCTION FOR GELS * See Sibayama, Tanaka & Han, J Chem Phys, (1992), 97(9), 6829-6841 * or Mallam, Horkay, Hecht, Rennie & Geissler, Macromol, (1991), 24, 543 include 'frills_sources:function.inc' real*8 lscale,gscale,zeta,rg,df,bkgd real*8 a,b,c,d,e lscale=p(1) gscale=p(2) * ZETA IS CORRELATION LENGTH IN LORENTZIAN zeta=p(3) * RG IS THE RADIUS OF GYRATION OF THE INHOMOGENEITIES rg=p(4) * DF IS THE FRACTAL EXPONENT * SCATTERING LAW REDUCES TO PURE LORENZTIAN IF DF=2 df=p(5) bkgd=p(6) if (df.le.0) then write(6,*)' ' write(6,*)'The Scaling Exponent must be >=0' write(6,*)'Will set to 2.' write(6,*)' ' df=2. end if do j=1,nv * LORENTZIAN TERM a=x(j)*x(j)*zeta*zeta b=(1.+(((df+1.)/3.)*a)) c=b**(df/2.) * EXPONENTIAL TERM d=x(j)*x(j)*rg*rg e=-1.*(d/3.) f=dexp(e) * SCATTERING LAW ycal(j)=(lscale/c)+(gscale*f)+bkgd end do return end