Journal Article Research Support, Non-U.S. Gov't density functional theory thermochemistry 789U1901C5 CCSD(T) CCSD(T)-based methods Copper G4 theory Organometallic Compounds Weizmann-4 theory automatic fitting basis set generation basis set convergence basis set superposition error (BSSE) complementary auxiliary basis set composite ab initio methods computational thermochemistry coupled cluster coupled cluster theory dispersion double hybrid double hybrids electron correlation explicitly correlated coupled cluster explicitly correlated methods noncovalent interactions partial charges platonic hydrocarbon cages post‐CCSD(T) correlation effects prismatic hydrocarbon cages