### Intermolecular interactions and force field development

The weak intermolecular interaction is of broad interest to the fields of chemistry and biology due to its role in the stabilization of supramolecular aggregates and of the spatial structure DNA bases and proteins. There are two different ways to calculate these interactions:

i-Supermolecular calculations especially at MP2, SCS-MP2 and CCSD(T) levels of theory

ii-Symmetry Adapted Perturbation Theory (SAPT), mainly DFT-SAPT implementation of Georg Jansen

Together with Forschergruppe 618, in our group we perform high accurate interaction energy calculations for small aggregates, e.g., acetylene, acetylene-benzene and benzene dimers.

Then we compute the full Potential Energy Surface (PES) of the dimers using the best theoretical method. This is followed by finding an approiate analytical functional form describing the interactions in the dimers. Such a high accurate force field can easily be used to determine the structures of aggragates of the dimer using the tools mentioned above.