Tight-binding model of Mn<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow/><mml:mn>12</mml:mn></mml:msub></mml:math>single-molecule magnets: Electronic and magnetic structure and transport properties
Bibliographic record
Abstract
We describe and analyze a tight-binding model of single-molecule magnets (SMMs) that captures both the spin and spatial aspects of the SMM electronic structure. The model generalizes extended H\"uckel theory to include the effects of spin polarization and spin-orbit coupling. For neutral and negatively charged Mn${}_{12}$ SMMs with acetate or benzoate ligands, the model yields the total SMM spin, the spins of the individual Mn ions, the magnetic easy axis orientation, the size of the magnetic anisotropy barrier, and the size of the highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO-LUMO) gap consistent with experiment. For neutral molecules, the predicted spins and spatial locations of the HOMO are consistent with the results of density functional calculations. For the total spin and location of the LUMO, density functional theory based calculations yield varied results, while the present model yields results consistent with experiments on negatively charged molecules. For Mn${}_{12}$ SMMs with thiolate- and methylsulphide-terminated benzoate ligands (Mn${}_{12}$-Ph-Th), we find the HOMO to be located on the magnetic core of the molecule, but (unlike for the Mn${}_{12}$ SMMs that have previously been studied theoretically) we predict the LUMO and near-LUMO orbitals of Mn${}_{12}$-Ph-Th to be located on ligands. Therefore, we predict that for these Mn${}_{12}$ SMMs, resonant and off-resonant coherent transport via near-LUMO orbitals, not subject to Coulomb blockade, should occur. We propose that this effect can be used to identify specific experimentally realized SMM transistors in which the easy axis and magnetic moment are approximately parallel to the direction of the current flow. We also predict effective spin filtering by these SMMs to occur at low bias whether the transport is mediated by the HOMO that is on the magnetic core of the SMM or by near-LUMO orbitals located on the nominally nonmagnetic ligands.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".