title: Coupled-cluster based basis sets for valence correlation calculations.
abstract: Novel basis sets are generated that target the description of valence correlation in atoms H through Ar. The new contraction coefficients are obtained according to the Atomic Natural Orbital (ANO) procedure from CCSD(T) (coupled-cluster singles and doubles with perturbative triples correction) density matrices starting from the primitive functions of Dunning et al. [J. Chem. Phys. 90, 1007 (1989); ibid. 98, 1358 (1993); ibid. 100, 2975 (1993)] (correlation consistent polarized valence X-tuple zeta, cc-pVXZ). The exponents of the primitive Gaussian functions are subject to uniform scaling in order to ensure satisfaction of the virial theorem for the corresponding atoms. These new sets, named ANO-VT-XZ (Atomic Natural Orbital Virial Theorem X-tuple Zeta), have the same number of contracted functions as their cc-pVXZ counterparts in each subshell. The performance of these basis sets is assessed by the evaluation of the contraction errors in four distinct computations: correlation energies in atoms, probing the density in different regions of space via ⟨r(n)⟩ (-3 ≤ n ≤ 3) in atoms, correlation energies in diatomic molecules, and the quality of fitting potential energy curves as measured by spectroscopic constants. All energy calculations with ANO-VT-QZ have contraction errors within "chemical accuracy" of 1 kcal/mol, which is not true for cc-pVQZ, suggesting some improvement compared to the correlation consistent series of Dunning and co-workers.
authors.affiliation: Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Claudino
authors.affiliation: Instituto de Física, Universidade de Brasília, CP04455, Brasília, DF, CEP 70919-970, Brazil.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Gargano
authors.affiliation: Quantum Theory Project, University of Florida, Gainesville, Florida 32611, USA.
authors.forename: Rodney J
authors.initials: RJ
authors.lastname: Bartlett