function HCTRecom(ion,nelem)
c     ============================
c
c     Code by Jim Kingdon, in collaboration with G.J. Ferland
c     ion is stage of ionization, 2 for the ion going to the atom
c     nelem is atomic number of element, 2 up to 30
c     Example:  O+ + H => O + H+ is HCTRecom(2,8)
c      integer ion , nelem
      INCLUDE 'IMPLIC.FOR'
      common/CTRTEMP/ te
      common/CTRecomb/ CTRecomb(6,4,30)
c
c     local variables
*      real tused 
c      integer ipIon
c
      ipIon = ion - 1
c
      if( ipIon.gt.4 ) then
c       use statistical charge transfer for ion > 4
        HCTRecom = 1.92e-9 * ipIon
        return
      endif
c
c     Make sure te is between temp. boundaries; set constant outside of range
      tused = max( te,CTRecomb(5,ipIon,nelem) )
      tused = min( tused , CTRecomb(6,ipIon,nelem) )
      tused = tused * 1e-4
c
c     the interpolation equation
      HCTRecom = CTRecomb(1,ipIon,nelem)* 1e-9 * 
     1 (tused**CTRecomb(2,ipIon,nelem)) *
     2 (1. + 
     3 CTRecomb(3,ipIon,nelem) * exp(CTRecomb(4,ipIon,nelem)*tused) )
c
      end