The lithium-thiophene interaction: a critical study using highly correlated electronic structure approaches of quantum chemistry

Michel Caffarel (1) , Anthony Scemama (1) , Alejandro Ramírez-Solís

1 GMO - Groupe THEO (LCPQ)

The fundamental multicentric interaction of a lithium atom with a single thiophene ring is addressed. A systematic study of the interaction energy (IE) and geometry for the Li-T charge-transfer complex is done at the MP2 and CCSD(T) levels using increasingly large basis sets up to aug-cc-pVQZ (AVQZ). Basis set superposition errors (BSSE) are evaluated and shown to have a major impact on the value of the IE. The Fixed-Node Diffusion Monte Carlo (FN-DMC) method is used as an alternative basis-set-free approach to obtain what is likely to be the most accurate estimate of the IE obtained so far. While counterpoise-corrected MP2/AVQZ and CCSD(T)/AVTZ interaction energies are found to be −3.8 and −7.5 kcal/mol, the FN-DMC method yields +1.3 ± 1.7 kcal/mol. The slow convergence of the ab initio IE (and some key structural parameters) with respect to basis set quality and the discrepancy with the FN-DMC result is discussed. A visualization of the electron pairing using the electron pair localization function (EPLF) for the Li-doped versus undoped thiophene is also presented.

Domaines: Chimie théorique et/ou physique

Michel Caffarel, Anthony Scemama, Alejandro Ramírez-Solís. The lithium-thiophene interaction: a critical study using highly correlated electronic structure approaches of quantum chemistry. Theoretical Chemistry Accounts: Theory, Computation, and Modeling, 2010, 126 (3-4), pp.275-287. ⟨10.1007/s00214-009-0713-y⟩. ⟨hal-00874606⟩