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Explicitly Correlated Coupled Cluster Calculations for Molecules Containing Group 11 (Cu, Ag, Au) and 12 (Zn, Cd, Hg) Elements: Optimized Complementary Auxiliary Basis Sets for Valence and Core–Valence Basis Sets

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journal contribution
posted on 14.02.2012, 00:00 by J. Grant Hill, Kirk A. Peterson
Compact auxiliary basis sets matched to the standard aug-cc-pVnZ-PP and aug-cc-pwCVnZ-PP orbital basis sets have been developed for the coinage metals (Cu, Ag, Au) and group 12 elements (Zn, Cd, Hg) for use in the resolution of the identity (RI) approximation in explicitly correlated F12 calculations. The CCSD­(T)-F12b method has been utilized with these auxiliary basis sets to carry out molecular benchmark calculations on homonuclear coinage metal diatomics (Cu2, Ag2, Au2), as well as mono- (CuF, AgF, AuF) and difluorides (CuF2, AgF2, AuF2). The resulting equilibrium geometries, harmonic vibrational frequencies, and atomization energies demonstrate that CCSD­(T)-F12b calculations using double-ζ-quality basis sets produce results comparable in accuracy to conventional CCSD­(T) quadruple-ζ calculations, while F12b with triple-ζ-quality sets yields results close to 5-ζ, which is near the conventional complete basis set (CBS) limit estimates. Analogous trends are observed for the group 12 monofluorides (ZnF, CdF, HgF). It is also shown that the effects of correlating the transition metal element (n – 1)­s and p electrons are relatively insensitive to the size of the basis set when the F12 method is utilized.