There are several methods to compute accurate global potential surfaces with the most successful being many-body expansions. But these methods, while general, are difficult to implement in an adaptive and general fashion for on-the-fly treatment of non-homogeneous systems with multiple components. To overcome such challenges we have developed an approach that uses a graphical decomposition of molecular structure. This helps to achieve both a molecular fragmentation procedure as well as a general, adaptive on-the-fly many-body approximation (a) that has been shown to provide MP2-level and CCSD-level AIMD trajectories at costs commensurate with DFT. (b) We obtain AIMD trajectories in agreement with large, triple-zeta basis sets (such as 6-311++G(2df,2pd)) at reduced cost commensurate with 6-31+G(d) for systems with more than hundred atoms. (c) The AIMD formalism is available in both Car-Parrinello-type extended-Lagrangian as well as Born-Oppenheimer flavors. (d) We have also generalized this procedure to treat condensed phase problems, especially those containing the interaction of solute molecules on surfaces, where we are able to obtain Rung-4 (hybrid) DFT accuracy at Rung-2-computational cost, with $k$-integration. (e) Using hyper-graphs, or a superposition of graphical decomposition of molecular structure, we construct potential energy surfaces, for the study of nuclear quantum effects, that are in agreement with post-Hartree-Fock levels of electronic structure theories at DFT cost. The method is described in the references below.

Graph-theoretic approach to automated and adaptive many-body expansions and generalizations to ONIOM: CCSD level AIMD at DFT cost, post-hartree-fock potential surfaces at DFT cost, and higher-rung DFT at pure DFT cost for condensed phase studies

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.