  Beryllium was recently discovered to harbor a Dirac nodal line (DNL) in its
bulk phase and the DNL-induced non-trivial drumhead-like surface states (DNSSs)
on its (0001) surface, rationalizing several already-existing historic puzzles
[Phys. Rev. Lett., \textbf{117}, 096401 (2016)]. However, to date the
underlying mechanism, as to why its (0001) surface exhibits an anomalously
large electron-phonon coupling effect ($\lambda_{e-ph}^s$ $\approx$ 1.0),
remains unresolved. Here, by means of first-principles calculations we have
evidenced that the coupling of the DNSSs with the phononic states mainly
contributes to its novel surface \emph{e-ph} enhancement. Besides that the
experimentally observed $\lambda_{e-ph}^s$ and the main Eliashberg coupling
function (ECF) peaks have been reproduced well, we have decomposed the ECF,
$\alpha^{2}$$F$(\emph{k},\textbf{\emph{q}};\emph{v}), and the \emph{e-ph}
coupling strength $\lambda(\emph{k},\textbf{\emph{q}};\emph{v})$ as a function
of each electron momentum (\emph{k}), each phonon momentum (\textbf{\emph{q}})
and each phonon mode ($v$), evidencing the robust connection between the DNSSs
and both $\alpha^{2}$$F$(\emph{k},\textbf{\emph{q}};\emph{v}) and
$\lambda(\emph{k},\textbf{\emph{q}};\emph{v})$. The results reveal the strong
\emph{e-ph} coupling between the DNSSs and the phonon modes, which contributes
over 80$\%$ of the $\lambda_{e-ph}^s$ coefficient on the Be (0001) surface. It
highlights that the anomalously large \emph{e-ph} coefficient on the Be (0001)
surface can be attributed to the presence of its DNL-induced DNSSs, clarifying
the long-term debated mechanism.
