output_exact_spectrum Subroutine

    subroutine output_exact_spectrum()

        use util_mod, only: get_free_unit

        integer :: i, temp_unit

        temp_unit = get_free_unit()
        open(temp_unit, file='EIGENVALUES', status='replace')
        write(temp_unit, '(1x,a12)') "Total energy"
        do i = 1, ndets_ed
            write(temp_unit, '(1x,i7,5x,f15.10)') i, eigv_ed(i)
        end do
        close(temp_unit)

    end subroutine output_exact_spectrum