Prototypical π–π dimers re-examined by means of high-level CCSDT(Q) composite <i>ab initio</i> methods
نویسندگان
چکیده
The benzene–ethene and parallel-displaced (PD) benzene–benzene dimers are the most fundamental systems involving π–π stacking interactions. Several high-level ab initio investigations calculated binding energies of these using coupled-cluster with singles, doubles, quasi-perturbative triple excitations [CCSD(T)] method at complete basis set [CBS] limit various approaches such as reduced virtual orbital spaces and/or MP2-based corrections. Here, we obtain CCSDT(Q) a Weizmann-3-type approach. In particular, extrapolate self-consistent field (SCF), CCSD, (T) components large heavy-atom augmented Gaussian sets [namely, SCF/jul-cc-pV{5,6}Z, CCSD/jul-cc-pV{Q,5}Z, (T)/jul-cc-pV{T,Q}Z]. We consider post-CCSD(T) contributions up to CCSDT(Q), inner-shell, scalar-relativistic, Born–Oppenheimer Overall, our best relativistic, all-electron ∆Ee,all,rel = 1.234 (benzene–ethene) 2.550 (benzene–benzene PD), ∆H0 0.949 2.310 ∆H298 0.130 1.461 PD) kcal mol−1. Important conclusions reached regarding convergence SCF, (T), components. Explicitly correlated calculations used sanity check on conventional energies. destabilizing by 0.028 0.058 (benzene–benzene) mol−1, thus, they cannot be neglected if sub-chemical accuracy is sought (i.e., errors below 0.1 mol−1). CCSD(T)/aug-cc-pwCVTZ core–valence corrections increase 0.018 0.027 Scalar-relativistic diagonal negligibly small. use evaluate performance MP2-based, CCSD-based, lower-cost composite procedures for obtaining challenging
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ژورنال
عنوان ژورنال: Journal of Chemical Physics
سال: 2021
ISSN: ['1520-9032', '1089-7690', '0021-9606']
DOI: https://doi.org/10.1063/5.0043046