!
  !----------------------------------------------------------------
  module parameters
  !----------------------------------------------------------------
  !
  integer, parameter :: dbl = selected_real_kind(14,200)
  integer, parameter :: DP = selected_real_kind(14,200)
  !
  integer, parameter :: nat = 2, nk = 165
  integer, parameter :: nbnd = 15
  !
  real(dbl), parameter :: alat = 10.26
  ! lattice parameter of silicon (5.43 A)
  ! without the factor 4 we have the volume of 8 atoms...
  real(dbl), parameter :: omega = 1080.49/4.d0 
  ! unit cell volume of silicon, bohr^3 
  real(dbl), parameter :: ecutwfc = 2.0  ! balde/tosatti: 2 Ry
  ! energy cutoff for wave functions in k-space ( in Rydbergs )
  ! 5 Ry and 40 Ry give essentially the same eps^-1(0,0,q)
  real(dbl), parameter :: ecut0 = 1.1 ! NOTE: ecut0 must be SMALLER than ecut 
  ! energy cutoff for trial diagonalization of Hamiltonian (input to CG - Rydbergs )
  real(dbl), parameter :: eps = 1.d-10
  ! threshold for conjugate gradient convergence
  integer, parameter :: maxter = 100
  ! max number of iterations in cong grad diagonalization
  !
  ! from: Cohen & Bergstresser, PRB 141, 789 (1966)
  !
  ! diamond structure - only the symmetric form factor is nonzero, Ry
  real(dbl), parameter :: v3 = -0.21, v8 = 0.04, v11 = 0.08
  !
  ! Haydock recursion parameters
  ! wmin, wmax, delta in eV
  !
  integer, parameter :: nstep = 100, nw = 1051
  real(DP), parameter :: wmin = -5.d0, wmax = 100.d0, delta = 0.1
  !
  ! variables for the screened Coulomb interaction
  !
  integer, parameter :: nq1 = 3, nq2 = 3, nq3 = 3, nbnd_occ = 4
  integer, parameter :: nk1 = 5, nk2 = 5, nk3 = 5
  integer, parameter :: k1 = 1, k2 = 1, k3 = 1    
  !
  integer, parameter :: nq = nq1 * nq2 * nq3
  integer, parameter :: nksq = nk1 * nk2 * nk3, nks = 2 * nksq  
  !
  integer, parameter :: DIRECT_IO_FACTOR = 8
  integer, parameter :: iunwfc = 78
  integer, parameter :: iubar = 80
  integer, parameter :: iudwf = 79
  integer, parameter :: iudwfp = 81
  integer, parameter :: iudwfm = 82
  !
  integer, parameter :: nmax_iter = 30
  ! max n. of iterations in solve_linter
  !
  integer, parameter :: nmix_ph = 4
  ! number of previous iterations used in modified Broyden mixing
  real(DP), parameter :: alpha_mix = 0.6
  ! parameter for potential mixing 
  real(DP), parameter :: tr2_ph = 1.d-10
  ! convergence threshold for dvscf
  !
  real(DP), parameter :: alpha_pv = 0.d0 !@ alpha_pv = 50.d0/13.606 
  ! parameter for the projection over the valence manifold
  ! this is to avoid null eigenvalues in (H-e+alpha_pv*P_v)dpsi
  ! in PH it is calculated as 2*(emax-emin)
 
  !
  ! threshold for the iterative solution of the linear system
  ! with thresh>1d-5 the potential does not converge
  !
  real(DP), parameter :: tr_cgsolve = 1.0d-14
  !

  !
  real(DP), parameter :: fmin = 0.d0, fmax = 25.d0
  ! frequency range for eps(\omega) plot - eV
  integer, parameter :: fbins = 10
  ! frequency bins
  real(DP), parameter :: eta = 0.01
  ! smearing for frequency dependent dielectric function - Ry
  !

  !
  end module parameters
  !