The Structure of VOPc on Cu(111): Does V=O Point Up, or Down, or Both?

P. J. Blowey; R. J. Maurer; L. A. Rochford; D. A. Duncan; J. H. Kang; D. A. Warr; A. J. Ramadan; T. L. Lee; P. K. Thakur; G. Costantini; K. Reuter; D. P. Woodruff

doi:10.1021/acs.jpcc.8b07530

The Structure of VOPc on Cu(111): Does V=O Point Up, or Down, or Both?

P. J. Blowey, R. J. Maurer, L. A. Rochford, D. A. Duncan, J. H. Kang, D. A. Warr, A. J. Ramadan, T. L. Lee, P. K. Thakur, G. Costantini, K. Reuter, D. P. Woodruff^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

11 Citations (Scopus)

Abstract

The local structure of the nonplanar phthalocyanine, vanadyl phthalocyanine (VOPc), adsorbed on Cu(111) at a coverage of approximately one-half of a saturated molecular layer, has been investigated by a combination of normal-incidence X-ray standing waves (NIXSW), scanned-energy mode photoelectron diffraction (PhD), and density-functional theory (DFT), complemented by scanning tunnelling microscopy (STM). Qualitative assessment of the NIXSW data clearly shows that both "up" and "down" orientations of the molecule (with V=O pointing out of, and into, the surface) must coexist on the surface. O 1s PhD proves to be inconclusive regarding the molecular orientation. DFT calculations, using two different dispersion correction schemes, show good quantitative agreement with the NIXSW structural results for equal co-occupation of the two different molecular orientations and clearly favor the many body dispersion (MBD) method to deal with long-range dispersion forces. The calculated relative adsorption energies of the differently oriented molecules at the lowest coverage show a strong preference for the "up" orientation, but at higher local coverages, this energetic difference decreases, and mixed orientation phases are almost energetically equivalent to pure "up"-oriented phases. DFT-based Tersoff-Hamann simulations of STM topographs for the two orientations cast some light on the extent to which such images provide a reliable guide to molecular orientation.

Original language	English
Pages (from-to)	8101-8111
Number of pages	11
Journal	Journal of Physical Chemistry C
Volume	123
Issue number	13
DOIs	https://doi.org/10.1021/acs.jpcc.8b07530
Publication status	Published - 4 Apr 2019

Bibliographical note

Funding Information:
The authors acknowledge the benefit of the award of beamtime on the Diamond Light Source (reference numbers SI9459, NT14524, and SI15899). They also gratefully acknowledge computing time on SuperMUC of the Bavarian Academy of Science and also on the Scientific Computing RTP at Warwick and the EPSRC-funded HPC Midlands Plus (EP/P020232/1). D.A.D. would like to acknowledge funding from the Alexander von Humboldt Foundation. P.J.B. acknowledges financial support from the Diamond Light Source and EPSRC. G.C. and D.A.W. acknowledge financial support from the EU through the European Research Council (ERC) Grant "VISUAL-MS."

Funding Information:
The authors acknowledge the benefit of the award of beamtime on the Diamond Light Source (reference numbers SI9459, NT14524, and SI15899). They also gratefully acknowledge computing time on SuperMUC of the Bavarian Academy of Science and also on the Scientific Computing RTP at Warwick and the EPSRC-funded HPC Midlands Plus (EP/P020232/1). D.A.D. would like to acknowledge funding from the Alexander von Humboldt Foundation. P.J.B. acknowledges financial support from the Diamond Light Source and EPSRC. G.C. and D.A.W. acknowledge financial support from the EU through the European Research Council (ERC) Grant “VISUAL-MS.”

Publisher Copyright:
Copyright © 2018 American Chemical Society.

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
General Energy
Physical and Theoretical Chemistry
Surfaces, Coatings and Films

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10.1021/acs.jpcc.8b07530

Cite this

@article{978583fc141243faaa84bb8fb6530c1d,

title = "The Structure of VOPc on Cu(111): Does V=O Point Up, or Down, or Both?",

abstract = "The local structure of the nonplanar phthalocyanine, vanadyl phthalocyanine (VOPc), adsorbed on Cu(111) at a coverage of approximately one-half of a saturated molecular layer, has been investigated by a combination of normal-incidence X-ray standing waves (NIXSW), scanned-energy mode photoelectron diffraction (PhD), and density-functional theory (DFT), complemented by scanning tunnelling microscopy (STM). Qualitative assessment of the NIXSW data clearly shows that both {"}up{"} and {"}down{"} orientations of the molecule (with V=O pointing out of, and into, the surface) must coexist on the surface. O 1s PhD proves to be inconclusive regarding the molecular orientation. DFT calculations, using two different dispersion correction schemes, show good quantitative agreement with the NIXSW structural results for equal co-occupation of the two different molecular orientations and clearly favor the many body dispersion (MBD) method to deal with long-range dispersion forces. The calculated relative adsorption energies of the differently oriented molecules at the lowest coverage show a strong preference for the {"}up{"} orientation, but at higher local coverages, this energetic difference decreases, and mixed orientation phases are almost energetically equivalent to pure {"}up{"}-oriented phases. DFT-based Tersoff-Hamann simulations of STM topographs for the two orientations cast some light on the extent to which such images provide a reliable guide to molecular orientation.",

author = "Blowey, {P. J.} and Maurer, {R. J.} and Rochford, {L. A.} and Duncan, {D. A.} and Kang, {J. H.} and Warr, {D. A.} and Ramadan, {A. J.} and Lee, {T. L.} and Thakur, {P. K.} and G. Costantini and K. Reuter and Woodruff, {D. P.}",

note = "Funding Information: The authors acknowledge the benefit of the award of beamtime on the Diamond Light Source (reference numbers SI9459, NT14524, and SI15899). They also gratefully acknowledge computing time on SuperMUC of the Bavarian Academy of Science and also on the Scientific Computing RTP at Warwick and the EPSRC-funded HPC Midlands Plus (EP/P020232/1). D.A.D. would like to acknowledge funding from the Alexander von Humboldt Foundation. P.J.B. acknowledges financial support from the Diamond Light Source and EPSRC. G.C. and D.A.W. acknowledge financial support from the EU through the European Research Council (ERC) Grant {"}VISUAL-MS.{"} Funding Information: The authors acknowledge the benefit of the award of beamtime on the Diamond Light Source (reference numbers SI9459, NT14524, and SI15899). They also gratefully acknowledge computing time on SuperMUC of the Bavarian Academy of Science and also on the Scientific Computing RTP at Warwick and the EPSRC-funded HPC Midlands Plus (EP/P020232/1). D.A.D. would like to acknowledge funding from the Alexander von Humboldt Foundation. P.J.B. acknowledges financial support from the Diamond Light Source and EPSRC. G.C. and D.A.W. acknowledge financial support from the EU through the European Research Council (ERC) Grant “VISUAL-MS.” Publisher Copyright: Copyright {\textcopyright} 2018 American Chemical Society.",

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doi = "10.1021/acs.jpcc.8b07530",

language = "English",

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AU - Maurer, R. J.

AU - Rochford, L. A.

AU - Duncan, D. A.

AU - Kang, J. H.

AU - Warr, D. A.

AU - Ramadan, A. J.

AU - Lee, T. L.

AU - Thakur, P. K.

AU - Costantini, G.

AU - Reuter, K.

AU - Woodruff, D. P.

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N2 - The local structure of the nonplanar phthalocyanine, vanadyl phthalocyanine (VOPc), adsorbed on Cu(111) at a coverage of approximately one-half of a saturated molecular layer, has been investigated by a combination of normal-incidence X-ray standing waves (NIXSW), scanned-energy mode photoelectron diffraction (PhD), and density-functional theory (DFT), complemented by scanning tunnelling microscopy (STM). Qualitative assessment of the NIXSW data clearly shows that both "up" and "down" orientations of the molecule (with V=O pointing out of, and into, the surface) must coexist on the surface. O 1s PhD proves to be inconclusive regarding the molecular orientation. DFT calculations, using two different dispersion correction schemes, show good quantitative agreement with the NIXSW structural results for equal co-occupation of the two different molecular orientations and clearly favor the many body dispersion (MBD) method to deal with long-range dispersion forces. The calculated relative adsorption energies of the differently oriented molecules at the lowest coverage show a strong preference for the "up" orientation, but at higher local coverages, this energetic difference decreases, and mixed orientation phases are almost energetically equivalent to pure "up"-oriented phases. DFT-based Tersoff-Hamann simulations of STM topographs for the two orientations cast some light on the extent to which such images provide a reliable guide to molecular orientation.

AB - The local structure of the nonplanar phthalocyanine, vanadyl phthalocyanine (VOPc), adsorbed on Cu(111) at a coverage of approximately one-half of a saturated molecular layer, has been investigated by a combination of normal-incidence X-ray standing waves (NIXSW), scanned-energy mode photoelectron diffraction (PhD), and density-functional theory (DFT), complemented by scanning tunnelling microscopy (STM). Qualitative assessment of the NIXSW data clearly shows that both "up" and "down" orientations of the molecule (with V=O pointing out of, and into, the surface) must coexist on the surface. O 1s PhD proves to be inconclusive regarding the molecular orientation. DFT calculations, using two different dispersion correction schemes, show good quantitative agreement with the NIXSW structural results for equal co-occupation of the two different molecular orientations and clearly favor the many body dispersion (MBD) method to deal with long-range dispersion forces. The calculated relative adsorption energies of the differently oriented molecules at the lowest coverage show a strong preference for the "up" orientation, but at higher local coverages, this energetic difference decreases, and mixed orientation phases are almost energetically equivalent to pure "up"-oriented phases. DFT-based Tersoff-Hamann simulations of STM topographs for the two orientations cast some light on the extent to which such images provide a reliable guide to molecular orientation.

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The Structure of VOPc on Cu(111): Does V=O Point Up, or Down, or Both?

Abstract

Bibliographical note

ASJC Scopus subject areas

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