  The anchoring of the molecule to an electrode is known to be a key factor in
single-molecule spintronics experiments. Likewise, a relaxation down to the
most stable geometry is a critical step in theoretical simulations of transport
through single-molecule junctions. Herein we present a set of calculations
designed to analyze and compare the effect of different anchoring points and
the effect of perturbations in the molecular geometry and interelectrode
distance. As model system we chose the [V($\alpha$-C$_3$S$_5$)$_3$]$^{2-}$
complex connecting two Au(111) electrodes in a slightly compressed geometry. In
our calculations, the attachment happens through an S-Au bond, a common
anchoring strategy in molecular spintronics experiments. Our results confirm
that small alterations in the molecular geometry have important effects in the
conductance. We were able to compare these effects with the ones arising from
changing the anchoring position with a constant molecular geometry.
Unexpectedly, we demonstrate that the anchoring position has only a lesser
relevance in the spintronic behavior of the device, as long as all other
parameters are kept frozen. As a consequence, we predict that for
experimentalists aiming for reproducibility, the molecular design of rigid
linkers is more relevant than the design of univocal anchoring positions.

Mesoscale and Nanoscale Physics