input_description -distribution {Quantum ESPRESSO} -package PWscf -program pw2gw.x {

    toc {}

    intro {

        @b {Purpose of pw2gw.x:}
           Optical properties in single-particle approach (Fermi Golden Rule).
           Interface with GW and excitonic codes.

           The code computes and writes ("matrixelements" file) the optical matrix elemenents in the 
           dipole approximation.

           The code computes the imaginary part of the dielectric tensor xx, yy and zz ("epsX.dat", "epsY.dat",
           "epsZ.dat") and the average ("epsTOT.dat")
          
        @b {Structure of the input data:}
        ============================

           @b &INPUTPP
             ...
           @b /
    }

    namelist INPUTPP {

        var prefix  -type        STRING {
            status { MANDATORY }
            info {
                the first part of the name of all the file written by the code
                should be equal to the value given in the main calculations.
            }
        }


        var outdir  -type        STRING {
            default { "./" }
            info {
                the scratch directory where the massive data-files are written
            }
        }


        var what  -type   STRING {
            default { "gw" }
            info {
                "gw" : Calculate dipole optical matrix elements (use for norm-conserving pseudopotentials)
                and imaginary part of the dielectric function.

                "gmaps": write g-maps for each processor in a file "fort.'100 + processor number'"
            }
        }

        var qplda  -type         LOGICAL {
            default { .FALSE. }
            info {
                if .TRUE. write the interface file "QPLDA" to GW and BSE codes (chisig, dpforexc).
            }
        }

        var vxcdiag  -type         LOGICAL {
            default { .FALSE. }
            info {
                if .TRUE. calculates the expectation value of the exchange and correlation potential
                on all the Kohn-Sham states and write it into the "vxcdiag.dat" file.
            }
        }

        var vkb  -type         LOGICAL {
            default { .FALSE. }
            info {
                if .TRUE. use Kleyman-Bylander projectors to write additional informatio into fort.15 file
            (Still in development)
            }
        }

        var Emin  -type         REAL {
            default { 0.0 }
            info {
                Starting photon energy for which the dielectric function is calculated (in eV)
            }
        }

        var Emax  -type         REAL {
            default { 30.0 }
            info {
                 Highest photon energy for which the dielectric function is calculated (in eV)
            }
        }

        var DeltaE  -type         REAL {
            default { 0.05 }
            info {
                Energy step with which the dielectric function is calculated (in eV)
            }
        }


    }
}
