Ab initio study of the gas-phase structure and electronic properties of M–CH3 (M=Li, Na) and M–CCH (M=Li, Na, K): A combined post-Hartree–Fock and density functional theory study

摘要: The structure of isolated, monomeric M–CH3 (M=Li, Na) and M–CCH (M=Li, Na, K) has been recently determined by millimeter/submillimeter rotational spectroscopy. These accurate experimental results offer the opportunity for an extensive ab initio study these molecules in order to assess accuracy latest developments density functional theory (DFT). As a general trend, DFT from hybrid functionals (B1LYP, mPW1PW91, PBE0) are very good agreement with experiment while conventional (BLYP) show slightly larger errors. In addition, methods rapid basis set convergence, whereas post-HF techniques [MP2, QCISD, CCSD(T)] give comparably only using large sets. properties derived electron computed fairly similar all methods, provided is used. importance proper treatment correlation description bond between carbon alkali metal atom emphasized.