Correlation Consistent Basis Sets for Explicitly Correlated Theory: The Transition Metals.

We present correlation consistent basis sets for explicitly correlated (F12) calculations, denoted VZ(-PP)-F12-wis ( = D,T), for the -block elements. The cc-pVDZ-F12-wis basis set is contracted to [8s7p5d2f] for the 3-block, while its ECP counterpart for the 4 and 5-blocks, cc-pVDZ-PP-F12-wis, is contracted to [6s6p5d2f]. The corresponding contracted sizes for cc-pVTZ(-PP)-F12-wis are [98632] for the 3-block elements and [77632] for the 4 and 5-block elements. Our VZ(-PP)-F12-wis basis sets are evaluated on challenging test sets for metal-organic barrier heights (MOBH35) and group-11 metal clusters (CUAGAU-2). In F12 calculations, they are found to be about as close to the complete basis set limit as the combination of standard cc-pVZ-F12 on with the standard aug-cc-pV(+1)Z(-PP) basis sets on the transition metal(s). While our basis sets are somewhat more compact than aug-cc-pV(+1)Z(-PP), the CPU time benefit is negligible for catalytic complexes that contain only one or two transition metals among dozens of main-group elements; however, it is somewhat more significant for metal clusters.