init_dispersion_rel_cache Subroutine

    subroutine init_dispersion_rel_cache()
        ! to avoid excessive calls to the cos() function cache the
        ! dispersion relation of the lattice and make them accessible
        ! through the symmetry label associated with the k-vectors!
        character(*), parameter :: this_routine = "init_dispersion_rel_cache"
        integer :: i, sym_min, sym_max, sym

        ASSERT(associated(lat))

        if (allocated(dispersion_rel_cached)) deallocate(dispersion_rel_cached)

        sym_min = 0
        sym_max = 0
        do i = 1, lat%get_nsites()
            sym = lat%get_sym(i)

            if (sym < sym_min) sym_min = sym
            if (sym > sym_max) sym_max = sym
        end do

        allocate(dispersion_rel_cached(sym_min:sym_max), source=0.0_dp)

        do i = 1, lat%get_nsites()
            dispersion_rel_cached(lat%get_sym(i)) = lat%dispersion_rel_orb(i)
        end do

    end subroutine init_dispersion_rel_cache