Quantum Monte Carlo Calculations of Catalytic Energy Barriers in a Metallorganic Framework with Transition-Metal-Functionalized Nodes

We have investigated electronic energy barriers for ethylene hydrogenation and C–H bond activation in transition-metal-functionalized Zr-based nodes in the NU-1000 metal–organic framework using quantum Monte Carlo (QMC) simulations. We compare our QMC results with results using density functional theory schemes. The density functional theory calculations can have errors up to 20 kcal/mol compared to the QMC calculations, underestimating the energy barrier for some reactions and overestimating the barrier for others. The hybrid functionals PBE0 and HSE06 generally perform best when compared with QMC, although they can still differ from the best QMC by 10 kcal/mol.