added ewald ref

Author: samarjeet

paper/basic_training.bib

@@ -985,6 +985,18 @@ @article{Isele-Holder:2012:JChemPhys
   pages = {174107},
 }
 
+@article{Ewald_1921,
+author = {Ewald, P. P.},
+title = {Die Berechnung optischer und elektrostatischer Gitterpotentiale},
+journal = {Annalen der Physik},
+volume = {369},
+number = {3},
+pages = {253-287},
+doi = {10.1002/andp.19213690304},
+url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/andp.19213690304},
+eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1002/andp.19213690304}
+}
+
 @article{Paliwal:2013:J.Chem.TheoryComput.,
   title = {Using {{Multistate Reweighting}} to {{Rapidly}} and {{Efficiently Explore Molecular Simulation Parameters Space}} for {{Nonbonded Interactions}}},
   volume = {9},

paper/basic_training.pdf

@@ -1024,9 +1024,8 @@ \subsubsection{Motivation}
 
 \subsubsection{ Ewald Summation}
 
-The Ewald summation technique [ref Ewald, 1921] provides one way to efficiently handle long-range electrostatics in periodic systems.
+The Ewald summation technique~\cite{Ewald_1921} provides one way to efficiently handle long-range electrostatics in periodic systems.
 To understand this technique, consider the relationship between the charge distribution and the Coulombic potential written in the differential form (the Poisson equation):
-\todo[inline, color={yellow!20}]{DLM: Fill in Ewald reference}
 
 \[
 \Delta \phi(\boldsymbol{x}) = - \frac{1}{\epsilon} \rho(\boldsymbol{x})