      function rjay(zetfac,gnoo)       
*
* Function to determine value of J for each element
*
      implicit double precision(a-h,o-z)

      if(gnoo.ge.-20.0 .and. gnoo.lt.0.d0)then
	zfac = zetfac
        rjnum = (0.0151/zfac)+(0.242/zfac**2.25)+(1.21/zfac**4.55)
        rjden = 1.d0 + 0.0371*dexp(0.906*gnoo)*(1.d0+0.928*zfac)
	rjay = rjnum*dexp(gnoo)/rjden
      elseif(gnoo .le. 10.0)then
        den = 1.d0+(-0.0120*gnoo)+(0.029*gnoo*gnoo)+(-0.00104*gnoo**3)
	zfac = zetfac/den
        rjnum = (0.0123/zfac)+(0.266/zfac**2.25)+(1.30/zfac**4.55)
        rjden = 1.d0 + 0.117*dexp(0.897*gnoo)*(1.d0+0.177*zfac)
	rjay = rjnum*dexp(gnoo)/rjden
      endif

      return      
      end 

************************************************************************
