There has been a growing interest in quantitative predictions of the intermolecular binding energy of large complexes. One of the most important quantum chemical techniques capable of such predictions is the domain-based local pair natural orbital (DLPNO) scheme for the coupled cluster theory with singles, doubles, and iterative triples [CCSD(T)], whose results are extrapolated to the complete basis set (CBS) limit. Here, the DLPNO-based focal-point method is devised with the aim of obtaining CBS-extrapolated values that are very close to their canonical CCSD(T)/CBS counterparts, and thus may serve for routinely checking a performance of less expensive computational methods, for example, those based on the density-functional theory (DFT). The efficacy of this method is demonstrated for several sets of noncovalent complexes with varying amounts of the electrostatics, induction, and dispersion contributions to binding (as revealed by accurate DFT-based symmetry-adapted perturbation theory (SAPT) calculations). It is shown that when applied to dimeric models of poly(3-hydroxybutyrate) chains in its two polymorphic forms, the DLPNO-CCSD(T) and DFT-SAPT computational schemes agree to within about 2 kJ/mol of an absolute value of the interaction energy. These computational schemes thus should be useful for a reliable description of factors leading to the enthalpic stabilization of extended systems.

• Klíčová slova
• CCSD(T), DFT-SAPT, DLPNO, intermolecular binding, noncovalent interactions,
• MeSH
• analýza nákladů a výnosů MeSH
• kvantová teorie * MeSH
• statická elektřina MeSH
• teorie funkcionálu hustoty MeSH
• termodynamika MeSH
• Publikační typ
• časopisecké články MeSH

The liquid state NMR chemical shift of protons is a parameter frequently used to characterize host-guest complexes. Its theoretical counterpart, that is, the 1H NMR chemical shielding affected by the solvent (1H CS), may provide important insights into spatial arrangements of supramolecular systems, and it can also be reliably obtained for challenging cases of an aggregation of aromatic and antiaromatic molecules in solution. This computational analysis is performed for the complex of coronene and an antiaromatic model compound in acetonitrile by employing the GIAO-B3LYP-PCM approach combined with a saturated basis set. Predicted 1H CS values are used to generate volumetric data, whose properties are thoroughly investigated. The 1H CS isosurface, corresponding to a value of the proton chemical shift taken from a previous experimental study, is described. The presence of the 1H CS isosurface should be taken into account in deriving structural information about supramolecular hosts and their encapsulation of small molecules.

• Klíčová slova
• B3LYP, GIAO, antiaromaticity, chemical shielding, proton NMR,
• MeSH
• acetonitrily chemie   MeSH
• difrakce rentgenového záření MeSH
• izotopy uhlíku MeSH
• magnetická rezonanční spektroskopie metody   MeSH
• makromolekulární látky MeSH
• nikl chemie   MeSH
• normální rozdělení MeSH
• polycyklické sloučeniny chemie   MeSH
• protonová magnetická rezonanční spektroskopie MeSH
• protony MeSH
• rozpouštědla chemie   MeSH
• železo chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• acetonitrile MeSH Prohlížeč
• acetonitrily MeSH
• Carbon-13 MeSH Prohlížeč
• coronene MeSH Prohlížeč
• izotopy uhlíku MeSH
• makromolekulární látky MeSH
• nikl MeSH
• polycyklické sloučeniny MeSH
• protony MeSH
• rozpouštědla MeSH
• železo MeSH