Seeing molecular orbitals

Pascual, José; Gómez-Herrero, Júlio; Rogero, Celia; Baró, A. M.; Sánchez‐Portal, Daniel; Artacho, Emilio; Ordejón, Pablo; Soler, Josep M.

doi:10.1016/s0009-2614(00)00337-7

Cited by 124 publications

(101 citation statements)

References 24 publications

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“…The image of the A-type HOMO orbital in Fig. 16 is also interesting because it is identical to a simulation made using DFT by Pascual et al [44]. In fact, the simple methods used here are able to reproduce all the images obtained using sophisticated DFT calculations in [44] and this fact gives us confidence in the procedures we have used.…”

Section: Effects Of Surface Interaction On Stm Imagessupporting

confidence: 69%

Jahn–Teller Effects in Molecules on Surfaces with Specific Application to C60

Hands

Dunn

Rawlinson

et al. 2009

Springer Series in Chemical Physics

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A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract Scanning tunnelling microscopy (STM) is capable of imaging molecules adsorbed onto surfaces with sufficient resolution as to permit intramolecular features to be discerned. Therefore, imaging molecules subject to the Jahn-Teller (JT) effect could, in principle, yield valuable information about the vibronic coupling responsible for the JT effect. However, such an application is not without its complications. For example, the JT effect causes subtle, dynamic distortions of the molecule; but how will this dynamic picture be affected by the host surface? And what will actually be imaged by the rather slow STM technique? Our aim here is to present a systematic investigation of the complications inherent in JT-related STM studies, to seek out possible JT signatures in such images and to guide further imaging towards identification and quantification of JT effects in molecules on surfaces. In particular, we consider the case of surface-adsorbed C 60 ions because of their propensity to exhibit JT effects, their STM-friendly size and because a better understanding of the vibronic effects within these ions may be important for realisation of their potential application as superconductors.

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Section: Effects Of Surface Interaction On Stm Imagessupporting

confidence: 69%

Jahn–Teller Effects in Molecules on Surfaces with Specific Application to C60

Hands

Dunn

Rawlinson

et al. 2009

Springer Series in Chemical Physics

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“…MOs are indeed unavoidable tools for understanding molecular bonding and structure and for discussing chemical and physical phenomena. Moreover, although this is not the case for virtual MOs, occupied orbitals can be "observed" by electron-momentum spectroscopy, [79,80] scanning tunnelling microscopy [81] and very recently by tomographic imaging based on femtosecond laser technology. [82] The different DFT calculations performed for a given M S value result in similar KS orbital energy levels.…”

Section: Ls and Hs Statesmentioning

confidence: 99%

Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex

et al. 2005

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In the iron(II) low‐spin complex [Fe(bpy)3]2+, the zero‐point energy difference between the 5T2g(t${{{4\hfill \atop 2g\hfill}}}$${e{{2\hfill \atop g\hfill}}}$) high‐spin and the 1A1g(t${{{6\hfill \atop 2g\hfill}}}$) low‐spin states, ΔE${{{0\hfill \atop HL\hfill}}}$, is estimated to lie in the range of 2500–5000 cm−1. This estimate is based on the low‐temperature dynamics of the high‐spin→low‐spin relaxation following the light‐induced population of the high‐spin state and on the assumption that the bond‐length difference between the two states ΔrHL is equal to the average value of ≈0.2 Å, as found experimentally for the spin‐crossover system. Calculations based on density functional theory (DFT) validate the structural assumption insofar as the low‐spin‐state optimised geometries are found to be in very good agreement with the experimental X‐ray structure of the complex and the predicted high‐spin geometries are all very close to one another for a whole series of common GGA (PB86, PW91, PBE, RPBE) and hybrid (B3LYP, B3LYP*, PBE1PBE) functionals. This confirmation of the structural assumption underlying the estimation of ΔE${{{0\hfill \atop HL\hfill}}}$ from experimental relaxation rate constants permits us to use this value to assess the ability of the density functionals for the calculation of the energy difference between the HS and LS states. Since the different functionals give values from −1000 to 12000 cm−1, the comparison of the calculated values with the experimental estimate thus provides a stringent criterion for the performance of a given functional. Based on this comparison the RPBE and B3LYP* functionals give the best agreement with experiment.

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“…Intramolecular C 60 resolution with threefold symmetry have been observed similarly with C 60 adsorbed on other substrates. 21,23 In particular, theoretical and experimental study of C 60 /Cu(111) indicates that the density of states are of doughnut shape for the highest-occupied molecular orbital and of threefold symmetry for the lowest unoccupied molecular orbital. 21 With the present system the intramolecular features signal that the electronic configurations and C 60 cage orientations of the bright and the dim molecules are different and possibly the electron transfer is not the same for those two cases.…”

Section: Fig 4 ͑A͒mentioning

confidence: 99%

“…[21][22][23][24][25] Quite frequently in the STM studies distinct C 60 species were discerned, i.e., molecules appearing with different imaging heights or intramolecular features. Since STM images a convolution of the surface electronic and geometric structure, it is often controversial as to whether the contrast is related simply to a difference in geometrical height ͑e.g., due to surface reconstruction͒ or to electronic effects ͑e.g., a spatially non-homogeneous density of states due to different adsorption sites or cage orientations͒.…”

Section: Introductionmentioning

confidence: 99%

Scanning tunneling microscopy and x-ray photoelectron diffraction investigation ofC60films on Cu(100)

et al. 2003

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Ultrathin C 60 films grown on a Cu͑100͒ surface in ultrahigh vacuum have been investigated by scanning tunneling microscopy ͑STM͒ and x-ray photoelectron diffraction ͑XPD͒. STM observations show that following deposition at room temperature C 60 molecules decorate substrate steps and order in densely packed extended islands and layers. Two kinds of contrast, i.e., different apparent heights, are encountered in the film evolution, which are associated with substrate reconstruction and inequivalent C 60 bonding. At elevated temperatures ͑500-600 K͒ a striped regular ( 0 4 10 6 ) superstructure is obtained comprising two distinct C 60 species.From an XPD analysis of this phase the corresponding possible C 60 bonding configurations could be determined.

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Seeing molecular orbitals

Cited by 124 publications

References 24 publications

Jahn–Teller Effects in Molecules on Surfaces with Specific Application to C60

Jahn–Teller Effects in Molecules on Surfaces with Specific Application to C60

Assessment of Density Functionals for the High‐Spin/Low‐Spin Energy Difference in the Low‐Spin Iron(II) Tris(2,2′‐bipyridine) Complex

Scanning tunneling microscopy and x-ray photoelectron diffraction investigation ofC60films on Cu(100)

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