Stability of the polyynic form of C 18 , C 22 , C 26 , and C 30 nanorings: a challenge tackled by range-separated double-hybrid density functionals

We calculate the relative energy between the cumulene and polyyne structures of a set of C ( = 4-7) rings (C , C , C , and C prompted by the recent synthesis of the cyclo[18]carbon (or simply C ) compounds. Reference results were obtained by a costly Quantum Monte-Carlo (QMC) approach, providing thu...

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Published in:Physical chemistry chemical physics : PCCP 2022-02, Vol.24 (7), p.4515-4525
Main Authors: Brémond, E, Pérez-Jiménez, A J, Adamo, C, Sancho-García, J C
Format: Article
Language:English
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Summary:We calculate the relative energy between the cumulene and polyyne structures of a set of C ( = 4-7) rings (C , C , C , and C prompted by the recent synthesis of the cyclo[18]carbon (or simply C ) compounds. Reference results were obtained by a costly Quantum Monte-Carlo (QMC) approach, providing thus very accurate values allowing to systematically compare the performance of a variety of wavefunction methods [( , MP2, SCS-MP2, SOS-MP2, DLPNO-CCSD, and DLPNO-CCSD(T)] as well as DFT approaches, applying for the latter a diversity of density functionals covering global and range-separated hybrid and double-hybrid models. The influence of the use of a range-separation scheme for density functionals, for both hybrid and double-hybrid expressions, is discussed according to its key role. Overall, range-separated double-hybrid functionals ( , RSX-QIDH) behave very accurately and provide competitive results compared with DLPNO-CCSD(T), at a more reasonable computational cost.
ISSN:1463-9076
1463-9084
DOI:10.1039/d1cp04996h