<h3>Title</h3>
<h3>Quantifying the impact of halogenation on intermolecular interactions of aromatic systems</h3>
<p><strong><span style="text-decoration: underline;">Abstract</span> :</strong></p>
<p>Recently, a new generation of self-assembled structures made up of perhalobenzenes (PHBs), C<sub>6</sub>X<sub>6</sub>, is reported that uses halogen bonding type interactions for self-assembly <sup>[1]</sup>. These molecules have a varied range of applications owing to their good optical and electrical properties because of their high electron affinity and diffuse electronic states <sup>[2,3]</sup>. PHB interactions involve X-X, π-π, and X-π interactions, leading to a complex interplay of intermolecular interactions. Here we quantify the relative binding energies for different conformations of PHBs, as a function of halogenation at the level of RPA-AXK. We observe that going from F to I the interaction energies increase four-fold with the parallel displaced conformation being the most stable one for all cases.  We also established high-level “benchmark” binding energies using the DLPNO-CCSD(T) method where we observe similar trends in the binding energies of dimers. However, we observed large percentage errors in the DLPNO-CCSD(T) binding energies compared to CCSD(T). These findings indicate that more caution is required in choosing so-called “benchmark method” while dealing with non-covalent interactions involving halogen bonding or molecules having large polarizability.</p>
<p> In addition, I will briefly discuss the work towards extending the applicability of response-function based methods for studying electron attachment energies of large systems. I will discuss the parallarization efforts using the corray feature of FORTRAN programming, and also developing computationally cheap approximations to GKS-spRPA<sup>[3-4]</sup> method.</p>
<p><strong> </strong><strong>References:</strong></p>
<p>[1] Teyssandier, J. <em>et. al.</em> <em>ChemistryOpen</em> <strong>2020</strong>, 9, 225–241</p>
<p>[2] Nyikos, L. <em>et. al.</em> <em>The Journal of Physical Chemistry</em> <strong>1980</strong>, 84, 1154–1155</p>
<p>[3] Voora, V. K. <em>The Journal of Physical Chemistry Letters</em> <strong>2020</strong>, 12, 433–439</p>
<p>[4] Voora, V. K. <em>et. al. Physical Review A, </em><strong>2019</strong>, 99(1)</p>