%0 Journal Article %A Glendening, E. D. %A Weinhold, F. %D 2019 %T Resonance Natural Bond Orbitals: Efficient Semilocalized Orbitals for Computing and Visualizing Reactive Chemical Processes %U https://acs.figshare.com/articles/journal_contribution/Resonance_Natural_Bond_Orbitals_Efficient_Semilocalized_Orbitals_for_Computing_and_Visualizing_Reactive_Chemical_Processes/7605374 %R 10.1021/acs.jctc.8b00948.s001 %2 https://acs.figshare.com/ndownloader/files/14120006 %K resonance theory %K bond shifts %K pattern %K Resonance Natural Bond Orbitals %K reactive chemical process %K NBO %K reactive bond-shifts %K MO-based expansion sets %K intramolecular Claisen rearrangement %K Lewis-structural character %K near-equilibrium species %K energy surface %K Visualizing Reactive Chemical Processes %K Efficient Semilocalized Orbitals %K multicenter character %K RNBO %K NRT %X We describe a practical algorithm for calculating NBO-based “resonance natural bond orbitals” (RNBOs) that can accurately describe the localized bond shifts of a reactive chemical process. Unlike conventional NBOs, the RNBOs bear no fixed relationship to a particular Lewis-structural bonding pattern but derive instead from the natural resonance theory (NRT)-based manifold of all bonding patterns that contribute significantly to resonance mixing (and associated multichannel reactivity) at a chosen point of the potential energy surface. The RNBOs typically retain familiar localized Lewis-structural character for stable near-equilibrium species, yet they freely adopt multicenter character as required to satisfy Pople’s prerequisite that no allowed computational basis set should be inherently biased toward a particular nuclear arrangement or bonding pattern. A simple numerical application to intramolecular Claisen rearrangement demonstrates the computational and conceptual advantages of describing reactive bond-shifts with RNBOs rather than other conventional NBO- or MO-based expansion sets. %I ACS Publications