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{To the Editors of the Journal of Chemical Physics}

\opening{Dear Editors,}

\justifying
Please find enclosed our manuscript entitled \textit{``Dynamical Correction to the Bethe-Salpeter Equation''}, which we would like you to consider as a Regular Article in the \textit{Journal of Chemical Physics}.
This contribution fits nicely in the section \textit{``Theoretical Methods and Algorithms''}. 
This contribution has never been submitted in total nor in parts to any other journal, and has been seen and approved by all authors.

The many-body Green's function Bethe-Salpeter equation (BSE) formalism is steadily asserting itself as a new efficient and accurate tool in the ensemble of computational methods available to chemists in order to predict optical excitations in molecular systems
In complete analogy with the ubiquitous adiabatic approximation in TD-DFT where the exchange-correlation kernel is made static, most of BSE implementations rely on the so-called static approximation, which approximates the dynamical (i.e., frequency-dependent) BSE kernel by its static limit.
One key consequence of the static approximation is that double (and higher) excitations are completely absent from the BSE optical spectrum, which obviously hampers the applicability of BSE as double excitation may play, indirectly, a key role in photochemistry mechanisms.
Going beyond the static approximation is tricky and very few groups have dared to take the plunge. 
In the present study, we propose a renormalized first-order perturbative correction to the static BSE excitation energies, which goes beyond the plasmon-pole approximation as the dynamical screening of the Coulomb interaction is computed exactly.
In order to assess the accuracy of the present scheme, we report a significant number of calculations for various molecular systems.
Our calculations are benchmarked against high-level (coupled-cluster) calculations, allowing to clearly evidence the improvements brought by the dynamical correction.

Because of the novelty of this part and its large impact in the electronic structure community (and beyond), we expect it to be of interest to a wide audience within the chemistry and physics communities.
We suggest Michael Rohlfing, Neepa Maitra, Patrick Rinke, Weitao Yang, Wim Klopper, Fabien Bruneval, and Lucia Reining as potential referees.
We look forward to hearing from you soon.

\closing{Sincerely, the authors.}


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