| 1. |
- Ferrighi, Lara, et al.
(author)
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Study of Alkylthiolate Self-Assembled Monolayers on Au(111) using a Semilocal meta-GGA Density Functional
- 2012
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 116:13, s. 7374-7379
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Journal article (peer-reviewed)abstract
- We present a density functional theory study of the structure and stability of self-assembled monolayers (SAMs) of alkylthiolate on Au(111) as a function of the alkyl chain length. The most favorable structure of the SAMs involves an RS−Au−SR complex (S being sulfur, R being an alkyl chain) formed through sandwiching one Au adatom by two alkylthiolates (RSs). Comparing a generalized gradient (GGA-PBE) and a meta-GGA (MGGA-M06-L) exchange-correlation functional we find that only the meta-GGA functional predicts the experimentally observed attractive intermolecular interactions within the SAMs. In particular, the use of M06-L yields an increased stability of the SAMs with increasing alkyl chain length and an increased attractive interaction between RS−Au−SR complexes at shorter distances.
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| 2. |
- Grånäs, Elin, et al.
(author)
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CO Intercalation of Graphene on Ir(111) in the Millibar Regime
- 2013
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 117:32, s. 16438-16447
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Journal article (peer-reviewed)abstract
- Here we show that it is possible to intercalate CO under graphene grown on Ir(111) already at room temperature when CO pressures in the millibar regime are used. From the interplay of X-ray photoelectron spectroscopy and scanning tunneling microscopy we conclude that the intercalated CO adsorption structure is similar to the (3 root 3 X 3 root 3)R30 degrees) adsorption structure that is formed on Ir(111) upon exposure to similar to 1 mbar of CO. Further, density functional theory calculations reveal that the structural and electronic properties of CO-intercalated graphene are similar to p-doped freestanding graphene. Finally we characterize nonintercalated stripes and islands that we always observe in the CO-intercalated graphene. We observe these nonintercalated areas predominately in HCP and FCC areas near step edges and suggest that stress release in graphene is the driving force for their formation, while the weak chemical bonds in HCP and FCC areas are the reason for their area selectivity.
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| 3. |
- Hjorth Larsen, Ask, et al.
(author)
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The atomic simulation environment-a Python library for working with atoms
- 2017
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In: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 29:27
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Research review (peer-reviewed)abstract
- The atomic simulation environment (ASE) is a software package written in the Python programming language with the aim of setting up, steering, and analyzing atomistic simulations. In ASE, tasks are fully scripted in Python. The powerful syntax of Python combined with the NumPy array library make it possible to perform very complex simulation tasks. For example, a sequence of calculations may be performed with the use of a simple 'for-loop' construction. Calculations of energy, forces, stresses and other quantities are performed through interfaces to many external electronic structure codes or force fields using a uniform interface. On top of this calculator interface, ASE provides modules for performing many standard simulation tasks such as structure optimization, molecular dynamics, handling of constraints and performing nudged elastic band calculations.
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