DFT Functionals for Modeling of Polyethylene Chains Cross-Linked by Metal Atoms. DLPNO–CCSD(T) Benchmark Calculations

Density functional theory (DFT) functionals for calculations of binding energies (BEs) the polyethylene (PE) chains cross-linked by selected metal atoms (M) are benchmarked against DLPNO–CCSD(T) and DLPNO–CCSD(T1) data. PEX-M-PEX complexes as compared with plain parallel PEX···PEX X = 3–9 carbon model species characterized a cooperative effect covalent C-M-C bonds interchain dispersion interactions. The accuracy DLPNO–CC methods was assessed comparison BEs canonical CCSD(T) results small PE3-M-PE3 complexes. Functionals closed-shell (M Be, Mg, Zn) were BEs; open-shell Li, Ag, Au) method iterative triples. Three corrections combined 25 DFT respect to PEX-M PEX fragments employing def2-TZVPP def2-QZVPP basis sets. Accuracy within 5% achieved five functionals. Less accurate complexes; only two deviate less than 15% from DLPNO–CCSD(T1). Particularly problematic PEX-Li-PEX A reasonable overall performance across all in terms mean absolute percentage error is found range-separated hybrid ωB97X-D3 CAM-B3LYP/D3(BJ)-ABC.