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| 2. |
- Baran, Jakub D., et al.
(författare)
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Density Functional Study of Metal-Phthalocyanines Interactions With a Silver Surface Ag(111).
- 2007
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Konferensbidrag (refereegranskat)abstract
- Metal phthalocyanines (MPc) are generally planar organic molecules comprising of a central metal atom surrounded by aromatic rings. Phthalocyanines are structurally similar to important biomolecules such as haemoglobin and chlorophyll and are commonly used in industry for pigmentation. They have been the focus of intense interest due to their electrical and (non-linear) optical properties. Deposited and/or slef-assembled on metal electrodes, phthalocyanines are attractive candidates for novel molecular sensors, memory, and light-harvesting components. Fundamental understanding of molecule-molecule and molecule-surface interaction is important when attempting to determine the charge transport characteristics of metal phthalocyanines. The most important are the interactions between first layer adsorbate molecules and the substrates, since these interactions determine the structural ordering of the organic films and therefore also have a considerable impact on the efficiency of optical, electronic, and magnetic properties of the system. To study the adsorption of metal-phthalocyanines (MPc (M=Co, Sn, Pb) on the Ag(111) surface we have performed electronic structure calculations using a cluster representation of the surface within the framework of density functional theory (DFT) [1]. Our calculations use the generalized gradient approximation (GGA) parameterization by Pedrew-Burke-Ernzerhof (PBE) for the exchange-correlation energy [2]. We have investigated bonding on three surface adsorption sites (hcp-hollow, fcc-hollow and on-top). SnPc was found to adsorb weakly to the surface, and to prefer hollow bonding rather than on-top bonding. The distance between the Sn atom and the top layer Ag-surface atoms (hcp-hollow and fcc-hollow) is consistent with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [3,4]. Adsorption of CoPc was found very site specific and to prefer the on-top binding site. The distance between the Co atom and the top layer Ag atoms is ~3 . For PbPc, successful adsorption was only obtained on the hcp-hollow site. For SnPc and PbPc binding energy is small fraction of eV, however CoPc bind much strongly to Ag(111) .For each of these systems we have found good agreement in binding geometries with experimental data
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| 3. |
- Baran, Jakub D., et al.
(författare)
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DFT Computation Of Metal-Phthalocyanines Bonded To Ag(111)
- 2007
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Konferensbidrag (refereegranskat)abstract
- To study the adsorption of metal-phthalocyanines (MPc (M=Co; Sn; Pb) on the Ag(111) surface we have performed electronic structure calculations using a cluster representation of the surface within the framework of density functional theory (DFT) [1]. Our calculations use the generalized gradient approximation (GGA) parameterization by Pedrew-Burke-Ernzerhof (PBE) for the exchange-correlation energy [2]. We have investigated bonding on three surface adsorption sites (hcp-hollow; fcc-hollow and on-top). SnPc was found to adsorb weakly to the surface (0.15 to 0.25 eV); and to prefer hollow bonding rather than on-top bonding. The distance between the Sn atom and the top layer Ag-surface atoms (hcp-hollow and fcc-hollow) is consistent with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [3;4]. CoPc is much more strongly bound to the Ag(111) surface and was found to prefer the on-top site. The calculated binding energy is 1.2 eV and the distance between the Co atom and the top layer Ag atoms is 3 (which also matched the experimental data well). For PbPc; successful adsorption was only obtained on the hcp-hollow site with a binding energy of 0.5 eV. For each of these systems we have found good agreement in binding geometries with experimental data.
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| 5. |
- Baran, Jakub D., et al.
(författare)
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Interactions of Metal-phthalocyanines MPc (M=Co; Sn; Pb) with Silver Surface Ag(111) : A Density Functional Study
- 2008
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Konferensbidrag (refereegranskat)abstract
- Deposited and/or self-assembled on metal electrodes; metal-phthalocyanine are attractive candidates for novel molecular sensors; memory; and light-harvesting components. The knowledge of the their molecular geometry and electronic structure are crucial points in order to understand their interactions with surfaces. To study the adsorption of metal-phthalocyanines (MPc (M=Co; Sn; Pb) bonded parallel on the Ag(111) surface we have performed electronic structure calculations using a cluster representation (55 and 169 silver atoms) of the surface within the framework of density functional theory (DFT) [1]. Our calculations use the generalized gradient approximation (GGA) parameterization by Pedrew-Burke-Ernzerhof (PBE) for the exchange-correlation energy [2] and multipole accelerated resolution of identity method [3]. We have investigated bonding on three surface adsorption sites (hcp-hollow; fcc-hollow and on-top). For each of these systems we have found good agreement in binding geometries with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [4;5]. Binding energies and geometries for all systems are given. We propose flat chemisorption of respective MPcs on Ag(111).
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| 8. |
- Baran, Jakub D., et al.
(författare)
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Theoretical and Experimental Study of Metal-phthalocyanines on Ag(111).
- 2009
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Konferensbidrag (refereegranskat)abstract
- Metal-phthalocyanines deposited and/or self-assembled on metal surface are considered as candidates for novel molecular sensors; molecular memories and photovoltaic cells. To study the adsorption of three metal-phthalocyanines (MPc (M=Co; Sn; Pb) on Ag(111) we performed density functional theory DFT calculations using the generalized gradient approximation (GGA) parameterization by Pedrew-Burke-Ernzerhof (PBE) for the exchange-correlation energy [1;2]. Three initial adsorption site were considered (hcp-hollow; fcc-hollow and on-top). Our results show that the most favourite adsorption site is hcp-hollow for SnPc and PbPc and on-top for CoPc. All calculated structures are compared with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [3;4] Good agreement in binding geometries with experiment was found. To understand the hybridization of MPc s molecular orbitals with silver orbitals we have compared selected partial density of states PDOS for a free and adsorbed MPcs. SnPc and PbPc hybridize mostly with surface by central metal atom; however the effect from the aromatic rings is not negligible. Adsorption of CoPc on the silver surface results in a transfer of electron density from the surface to the central Co atom. After adsorption; the magnetic moment of CoPc is completely quenched which is in agreement with similar studies on adsorption on Au(111) [5]. Binding energies for all of systems are reported showing chemisorptive nature of the molecule-metal surface interaction
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| 9. |
- Baran, Jakub D., et al.
(författare)
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Theoretical Study Of Metal-Phthalocyanies MPc (M=Co; Sn; Pb) With Silver Surface Ag(111) And Reversible Conformational Inversion
- 2008
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Konferensbidrag (refereegranskat)abstract
- Metal-phthalocyanie adsorbed on metal surfaces are class of materials particularly promising as a building blocks for molecular electronic devices. Their application rely on the electrochemically induced switching of their electronic and magnetic state has been demonstrated [1]. The knowledge of their molecular geometry and electronic structure as a single entities and when adsorbed on surface are crucial points in order to understand their interaction with surfaces. By means of density functional theory (DFT) we have investigated conformational interconversion ( see Fig. 1) of single MPc molecules as their interaction with Ag(111) silver surfaces. Structural analysis using B3-LYP functional; and DZVP2 and TZVPP2 [2] basis set has been performed to evaluate the transition state (TS) and energy barrier of this conversion. We have found two different mechanism of inversion for SnPc and PbPc. To study the adsorption of metal-phthalocyanies MPc (M=Co; Sn; Pb) bonded parallel to the Ag(111) surface we used cluster representation of surface (55 and 169 silver atoms). To perform this calculations the generalized gradient approximation (GGA) parameterisation by Pedrew-Burke-Ernzerhof (PBE) for exchange-correlation energy [3] and multipole resolution of identity [4] method were used. We have investigated bonding on three surface adsorption sites (hcp-hollow; fcc-hollow and on-top). For each of these systems we have found good agreement in binding geometries with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [4;5]. Binding energies and geometries for all systems are given. We have used electronic structure calculations to better understand these molecules as a separate entities and as a devices
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