Deciphering the origin of variation in the spin ground state and oxidation state of a {Mn₁₉} cluster on a Au(111) surface: is the Au(111) surface innocent?

Abstract

Modeling the structure of a {Mn19} cluster on an Au(111) surface reveals that exchange coupling constants vary grossly upon adsorption due to surface-induced structural distortions. This leads to significant variations in the ground state S values.

The Decisive Role of Spin States and Spin Coupling in Dictating Selective O2 Adsorption in Chromium(II) Metal–Organic Frameworks**

“…This methodology has proven to yield very good geometries for open‐shell MOFs and has shown to yield a good numerical estimate of exchange coupling constants ( J ) [38,39] . Our earlier studies on [Mn 19 ] clusters reveal that the combination of PBE with plane‐wave basis sets yields J values which are similar to the estimate obtained from B3LYP employing Gaussian‐type basis set [40] . To further assess, we have performed a limited benchmarking on a model complex (Table S1 in the Supporting Information), which supports the view that PBE yields a better estimate, though the magnitude is overestimated.…”

Decisive Role of Spin-States and Spin-Coupling in Dictating Selective O2 Adsorption in Chromium(II) Metal-Organic Framework

“…The boundary conditions a=b=c, which is set as 18.6695 Å. 17 Our earlier studies on [Mn19] cluster reveal that the combination of PBE with plane-wave basis sets yields J values which are similar to the estimate obtained from B3LYP employing Gaussian type basis set. The PBE functional with the plane-wave basis set is shown to offer less delocalization, perhaps due to confinement, and this improves the numerical estimate of J compared to hybrid B3LYP functional.…”

“…This benchmark established by Ruiz et al and also by us earlier offers confidence in the methodology chosen. [17][18] Adsorption isotherms were simulated through the Grand Canonical Monte Carlo technique as implemented in the RASPA software. 19 The Lennard−Jones (LJ) parameters for the considered framework atoms were taken from Universal Force Field (UFF), 20 , and Lorentz-Berthelot mixing rules are used to calculate the cross interactions.…”

Design Considerations for Oligo(p-Phenyleneethynylene) Organic Radicals in Molecular Junctions

“…Finally, it would be highly interesting for future work to study the effect of these radical substituents on the spin-polarization of thiol-gold interfaces [67][68][69][70][71], which might alter the conductance properties beyond the purely molecule-centered effects studied here.…”

“…Since also in single-molecule conductance measurements, the molecule bridging between the electrodes is typically surrounded by other molecules of the same type due to the preparation process, intermolecular interactions and cooperative effects could also play a role in (formally) single-molecule experiments. It has also been suggested based on DFT calculations that the surface could play a noninnocent role in thiol adsorption on gold, possibly leading to spin polarization at the interface [67][68][69][70][71], which might interact with the spin on the molecule [68]. Also, a radical could loose its spin when attached to a metal surface [72], which can depend subtly on the details of the environment [73].…”