TY - JOUR
T1 - Performance of Localized Coupled Cluster Methods in a Moderately Strong Correlation Regime
T2 - Huckel-Mobius Interconversions in Expanded Porphyrins
AU - Sylvetsky, Nitai
AU - Banerjee, Ambar
AU - Alonso, Mercedes
AU - Martin, Jan M.l.
N1 - M. A. thanks the FWO for a postdoctoral fellowship (12F4416N) and the VUB for financial support. Research at Weizmann was funded by the Israel Science Foundation (grant 1358/15) and by the Estate of Emile Mimran (Weizmann), while computational resources and services were provided by Chemfarm (the Weizmann Institute Faculty of Chemistry HPC facility). AB and NS acknowledge postdoctoral and doctoral fellowships, respectively, from the Feinberg Graduate School at the Weizmann Institute. The authors would like to thank Prof. HansJoachim Werner (U. of Stuttgart, Germany) for helpful discussions and Dr. Peter Nagy (TU Budapest, Hungary) for extensive assistance with the MRCC program system. Dr. Mark Vilensky (scientific computing manager of ChemFarm) is thanked for his assistance with the somewhat exorbitant mass storage requirements of the largest canonical calculations. Equally contributing first authors: Nitai Sylvetsky, Ambar Banerjee
PY - 2020/6/9
Y1 - 2020/6/9
N2 - Localized orbital coupled cluster theory has recently emerged as a nonempirical alternative to DFT for large systems. Intuitively, one might expect such methods to perform less well for highly delocalized systems. In the present work, we apply both canonical CCSD(T) approximations and a variety of localized approximations to a set of flexible expanded porphyrins - macrocycles that can switch between Hückel, figure-eight, and Möbius topologies under external stimuli. Both minima and isomerization transition states are considered. We find that Möbius(-like) structures have much stronger static correlation character than the remaining structures, and that this causes significant errors in DLPNO-CCSD(T) and even DLPNO-CCSD(T1) approaches, unless TightPNO cutoffs are employed. If sub-kcal mol-1 accuracy with respect to canonical relative energies is required even for Möbius-type systems (or other systems plagued by strong static correlation), then Nagy and Kallay's LNO-CCSD(T) method with "tight"settings is the suitable localized approach. We propose the present POLYPYR21 data set as a benchmark for localized orbital methods or, more broadly, for the ability of lower-level methods to handle energetics with strongly varying degrees of static correlation.
AB - Localized orbital coupled cluster theory has recently emerged as a nonempirical alternative to DFT for large systems. Intuitively, one might expect such methods to perform less well for highly delocalized systems. In the present work, we apply both canonical CCSD(T) approximations and a variety of localized approximations to a set of flexible expanded porphyrins - macrocycles that can switch between Hückel, figure-eight, and Möbius topologies under external stimuli. Both minima and isomerization transition states are considered. We find that Möbius(-like) structures have much stronger static correlation character than the remaining structures, and that this causes significant errors in DLPNO-CCSD(T) and even DLPNO-CCSD(T1) approaches, unless TightPNO cutoffs are employed. If sub-kcal mol-1 accuracy with respect to canonical relative energies is required even for Möbius-type systems (or other systems plagued by strong static correlation), then Nagy and Kallay's LNO-CCSD(T) method with "tight"settings is the suitable localized approach. We propose the present POLYPYR21 data set as a benchmark for localized orbital methods or, more broadly, for the ability of lower-level methods to handle energetics with strongly varying degrees of static correlation.
U2 - https://doi.org/10.1021/acs.jctc.0c00297
DO - https://doi.org/10.1021/acs.jctc.0c00297
M3 - مقالة
C2 - 32338891
SN - 1549-9618
VL - 16
SP - 3641
EP - 3653
JO - Journal of Chemical Theory and Computation
JF - Journal of Chemical Theory and Computation
IS - 6
ER -