Simulating excited states in metal organic frameworks: from light-absorption to photochemical CO 2 reduction Michael Ingham 1 , Alex Aziz 2 , Devis Di Tommaso 3 , Rachel Crespo-Otero 1 Department of Chemistry, University of College London, UK, Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Japan, Department of Chemistry, Queen Mary University of London, UK Metal-organic frameworks (MOFs) hold promise in a wide range of photocatalytic and optoelectronic applications, many directly dependent on their excited states. However, simulating the excited states of MOFs is challenging due to large and complex unit cells,the inherent molecule/crystal duality of MOFs, and the unfavourable scalability of quantum chemical methods.[1]However, periodic and cluster modelshave been developed and applied to characterise the excited states of MOFs and their properties, such ascharge transfer, luminescence, and photocatalytic mechanisms. In particular, the highly localised electronicstructure of MOFs means their excited states can often be effectively simulated using truncated cluster models, andthe use of embedding techniques, such as ONIOM(QM:QM’), can further refine accuracy byincorporating the wider crystal environment. Here, we investigate the performance of cluster and periodicmodels in simulating MOF excited states through an exemplary MOF, comparing results at different levelsof theory from the cluster, embedding, and periodic perspectives. In particular, we highlight the efficacy ofusing range-separated hybrid functionals in TDDFT calculations. Finally, we extend our own excited-stateONIOM code, fromage,[2,3] to MOFs and other coordination polymers, and implement new self-consistentpoint charge embedding schemes.[4]In future work, we seek to extend these results by leveraging machinelearning techniques. References 1. M. Ingham, A. Aziz, D. Di Tommaso, R. Crespo-Otero,Mater.Adv., 2023,submitted.M. Rivera, M. Dommett, A. Sidat, W. Rahim and R. Crespo-Otero, J. Comput. Chem., 2020, 41, 2. 1045–1058.M. Rivera, M. Dommett and R. Crespo-Otero, J. Chem. Theory Comput., 2019, 15, 2504–2516.A. Biancardi, J. Barnes and M. Caricato, J.Chem.Phys., 2016, 145, 224109.
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