/** \brief template for function documentation

    Functions should exactly descibe the implemented algoriths. If possible
    use ::lists, ::latex, ::biblio, and ::images. 

    In addition the function arguments and return values have to be specified.
    Lists or arrays have to specify the storage order, e.g.  (iSpecies)(iAtom)

    \author John Doe, johndoe@domain.org
    \param  iteration   current iteration number 
    \param  eps         one particle energy value \f$ 
                            \epsilon = \langle \Psi | H | \Psi \rangle 
                        \f$
    \param  atoms       (iSpecies)(iAtom), list of atoms
    \return             converged total energy in Hartree
    \sa     lists
    \sa     latex
    \sa     biblio
    \sa     images */
    double functions (int iteration, 
                      double eps, 
                      const SxArray<SxArray<double> > &atoms);
