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

We present correlation
consistent basis sets for explicitly correlated
(F12) calculations, denoted VnZ(-PP)-F12-wis (n = D,T), for the d-block elements. The
cc-pVDZ-F12-wis basis set is contracted to [8s7p5d2f] for the 3d-block, while its ECP counterpart for the 4d and 5d-blocks, cc-pVDZ-PP-F12-wis, is contracted
to [6s6p5d2f]. The corresponding contracted sizes for cc-pVTZ(-PP)-F12-wis
are [9s8p6d3f2g] for the 3d-block
elements and [7s7p6d3f2g] for the 4d and 5d-block elements. Our VnZ(-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-pVnZ-F12 on main-group elements with the standard aug-cc-pV(n+1)Z(-PP) basis sets on the transition metal(s). While
our basis sets are somewhat more compact than aug-cc-pV(n+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.