Local explicitly correlated coupled-cluster methods: Efficient removalof the basis set incompleteness and domain errors

摘要

We propose an explicitly correlated local LCCSD-F12 method in which the basis set incompletenesserror as well as the error caused by truncating the virtual orbital space to pair-specific local domainsare strongly reduced. This is made possible by including explicitly correlated terms that areorthogonalized only to the pair-specific configuration space. Thus, the contributions of excitationsoutside the domains are implicitly accounted for by the explicitly correlated terms. It isdemonstrated for a set of 54 reactions that the reaction energies computed with the new LCCSD-F12method and triple-zeta basis sets deviate by at most 2.5 kJ/mol from conventional CCSD completebasis set results (RMS: 0.6 kJ/mol). The local approximations should make it possible to achievelinear scaling of the computational cost with molecular size.