1. E /eV u^-1
2. sigma /cm²

• B57: R. K. Janev, J. J. Smith, F. Aumayr, D. Wutte, M. Schneider, H. P. Winter, J. Schweizer, "Atomic collision database for Li beam interaction with fusion plasmas", IAEA, Vienna 267 (1993). [https://www-nds.iaea.org/publications/indc/indc-nds-0267/]

def hloss2(pe, pcf, kncf):
    """
    This function calculates the cross-section (cm2) for electron removal.

    pe: collision energy in eV/amu
    pcf: parameter data array
        pcf[0:3]: parameters for fit to the cross section
    """    
    if pe < 0.0:
        pxs = 0.0
        warnings.warn('Collision energy (pe) must be greater than or equal to zero.')
        return pxs

   #change the energy in keV
    e = pe * 1.0e-03   
    # Determine the value of the cross section pxs
    if kncf == 3:
        xs1 = pcf[0] * (1.0 - np.exp(-pcf[1] * np.log(np.exp(1.0) + pcf[2] * e) / e))
        pxs = 1.0e-14 * xs1
    else:
        raise ValueError('Incorrect number of coefficients passed to hloss2')
    
    return pxs

c
c###################################################################
c
      subroutine hloss2(pe, pcf, kncf, pxs, kermsg)
c
c     this is a subroutine to calculate cross sections (cm[2])
c     versus energy (eV) for electron removal.
c
c     pe = collision energy in eV/amu
c
c     pcf(1-3) = A1 - A3
c
c    - warning- .
c
c     the coefficient array pcf is updated by this routine to
c     include energy independent constants. these coefficients can be
c     used in subsequent calls for the same entry.
c
c     kermsg = blank if no errors
c
c     pxs = cross section in cm[2]
c
c------------------------------------------------------------------------
c
      double precision e, pe, pcf, pxs
      double precision xs1
      double precision a1, a2, a3
c
      dimension pcf(3)
      character*(*) kermsg
c
      if(pe .ge. 0.0) then
        kermsg = ' '
      else
        pxs = 0.0
        return
      endif
c
c generate the energy in keV
c
      e = pe*1.0e-03
c
c     determine the value of the cross section  pxs
c
      if(kncf .eq. 3) then
        a1 = pcf(1)
        a2 = pcf(2)
        a3 = pcf(3)
        xs1 = a1 * (1.d0 - dexp(-a2*dlog(dexp(1.d0) + a3*e)/e))
        pxs = 1.0e-14 * xs1 
      else
          kermsg = ' incorrect number of coefficients passed to hloss2'
          return
      endif
c
      return
      end