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Quantum Theory Calculations of
Supported Transition-Metal
Clusters
Dr. Yohanna Seminovski Perez,
Dr. Polina Tereshchuk,
Pr...
Members:
-Prof. Dr. Juarez L. F. Da Silva
-Posdocs: Dr. Yohanna Dr. Polina Dr. Anderson S.
Seminovski Tereshchuk Chaves
-P...
Research Projects
Clusters and Nanoclusters
- Transition-metals.
- Oxides and binary systems.
- Global optimization algori...
Computational Details
Density Functional Theory – DFT
- Semilocal XC functionals: PBE, PW91.
- Hybrid functionals: PBE0, H...
Importance and Challenges of TM/CeO2
(111) supports
● This interfacial interaction can be theoretically described.
Importa...
TM4
/CeO2
(111): 2D vs. 3D TM over CeO2
Ru4
/CeO2
(111)
Rh4
/CeO2
(111)
Os4
/CeO2
(111)
Ir4
/CeO2
(111)
Pd4
/CeO2
(111)
Pt...
Pt4
/CeO2
(111): Electronic structure
electronic LDOS of CeIII
states
TM states hibridized with O states
M.J. Piotrowski, ...
P. Tereshchuk, R.L.H. Freire, C.G. Ungureanu, Y. Seminovski, A. Kiejna, J.L.F. Da Silva, Phys.
Chem. Chem. Phys. (2015) DO...
Flow of electronic charges on TM13
/CeO2
(111)
TM13
-cluster stacking:
TM/TM4
/TM8
/CeO2
(111)
P. Tereshchuk, R.L.H. Freir...
● In TM4
/CeO2
(111) the 2D and 3D TM structures have an atomic
arrangement due to the interaction with the surface, which...
Publications
● P. Tereshchuk, R.L.H. Freire, C.G. Ungureanu, Y. Seminovski, A. Kiejna, J.L.F. Da Silva, Phys.
Chem. Chem. ...
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“Quantum Theory Calculations of Supported and Unsupported Transition-Metal Clusters”. Dra. Yohanna Seminovski Pérez – IQSC/USP.

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“Quantum Theory Calculations of Supported and Unsupported Transition-Metal Clusters”, presented at http://3whpc.lcca.usp.br

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“Quantum Theory Calculations of Supported and Unsupported Transition-Metal Clusters”. Dra. Yohanna Seminovski Pérez – IQSC/USP.

  1. 1. Quantum Theory Calculations of Supported Transition-Metal Clusters Dr. Yohanna Seminovski Perez, Dr. Polina Tereshchuk, Prof. Dr. Juarez L. F. Da Silva QTNano Quantum Theory of Nanomaterials Group São Carlos Institute of Chemistry University of São Paulo
  2. 2. Members: -Prof. Dr. Juarez L. F. Da Silva -Posdocs: Dr. Yohanna Dr. Polina Dr. Anderson S. Seminovski Tereshchuk Chaves -PhD students: Rafael L.H. Diego G. Fernando P. Celso R. Freire Sobrinho Sabino Rego -Msc students: Larissa Z. Israel Douglas G. Rafael Besse Rosalino de Souza Besse Computational Resources: - Local SGI cluster - LCCA Aguia cluster - USP-Rice Bluegene Collaborators: - Prof. Dr. Adam Kiejna, U. Wrocław, Poland - Prof. Dr. Maurício J. Piotrowski, UFPel, Brazil - Prof. Dr. Luiz Nunes de Oliveira, IFSC, USP, Brazil - Prof. Dr. Marcelo Falcão de Oliveira, EESC, USP, Brazil Quantum Theory of Nanomaterials Group
  3. 3. Research Projects Clusters and Nanoclusters - Transition-metals. - Oxides and binary systems. - Global optimization algorithms. - Thermodynamic properties. Surfaces - Clean surface properties. - Transition-metal supported on surfaces. - Molecular adsorption on surfaces. Solids - Transparent conducting oxides. - Wide-band gap semiconductors.
  4. 4. Computational Details Density Functional Theory – DFT - Semilocal XC functionals: PBE, PW91. - Hybrid functionals: PBE0, HSE. - Orbital dependent LDA+U functional. - van der Waals corrections (S. Grimme, TS-SCS). - Spin-orbit coupling for valence states. Kohn-Sham equations - Plane waves: VASP. - Numeric atom-centered basis functions: FHI-AIMS. Local and Global optimizations algorithms - GOP - Revised Basin Hopping Monte Carlo – RBHMC. - Genetic Algorithm - GA.
  5. 5. Importance and Challenges of TM/CeO2 (111) supports ● This interfacial interaction can be theoretically described. Importance and Challenges of TM/CeO2 (111) supports are related with Ce atom: ● The conditions in which this happens are going to be described using DFT+U approach. ● In VASP DFT code, we used an effective U, Ueff=4.5 eV within the Dudarev approach of DFT+U. CeO2 Metal Oxide Support TM Cluster BSASBS ● TM/CeO2 (111) supports have a characteristic synergistic effect useful for catalysis of reactions. Interface Synergy Ce-4f valence state is delocalized in unreduced CeO2 (111), but these states can also allocate strongly correlated localized charges.
  6. 6. TM4 /CeO2 (111): 2D vs. 3D TM over CeO2 Ru4 /CeO2 (111) Rh4 /CeO2 (111) Os4 /CeO2 (111) Ir4 /CeO2 (111) Pd4 /CeO2 (111) Pt4 /CeO2 (111) Ag4 /CeO2 (111) Au4 /CeO2 (111) M.J. Piotrowski, P. Tereshchuk, J.L.F. Da Silva, J. Phys Chem C 118 (2014) 21438 2D-Monolayer - In TM 2D-Monolayer: there is an equidistant CeIII generation. - In TM 3D-Cluster: Generation of one CeIII for Pt and Pd and two for Au and Ag. 3D-Cluster Transition Metal of group 6 and 7 Partially filled d-orbitals Transition Metal of group 8 and 9 Almost completely filled d-orbitals For Pd and Pt cases (8 group): For Au and Ag (9 group): For Ru,Rh,Os and Ir:
  7. 7. Pt4 /CeO2 (111): Electronic structure electronic LDOS of CeIII states TM states hibridized with O states M.J. Piotrowski, P. Tereshchuk, J.L.F. Da Silva, J. Phys Chem C 118 (2014) 21438
  8. 8. P. Tereshchuk, R.L.H. Freire, C.G. Ungureanu, Y. Seminovski, A. Kiejna, J.L.F. Da Silva, Phys. Chem. Chem. Phys. (2015) DOI: 10.1039/C4CP06016D 13-atoms TM-clusters (TM13 ) A 4x4 unit-cell of unreduced CeO2 (111) surface ● CeIII are slightly bigger than CeIV creating some strains in the surface. 3D-Pyramidal structure 2D-Structures TM13 /CeO2 (111): 2D vs. 3D TM over CeO2 3 CeIII are located in the topmost Ce layer. TM13 of Ag, Au, Pt and Pd show a pyramid like structure as the most stable. Calculations: Erel=Most stable Erel=
  9. 9. Flow of electronic charges on TM13 /CeO2 (111) TM13 -cluster stacking: TM/TM4 /TM8 /CeO2 (111) P. Tereshchuk, R.L.H. Freire, C.G. Ungureanu, Y. Seminovski, A. Kiejna, J.L.F. Da Silva, Phys. Chem. Chem. Phys. (2015) DOI: 10.1039/C4CP06016D 3- Ce f-states change from itinerant to localized (from CeIV to CeIII ) 4- Important to notice is that the pressure of the TM13 - clusters decreases the charge of the underlying O-ions and increases in the remaining O- ions. e- e- e- 1- Flow of electronic charge from TM13 cluster to CeO2 (111) due to electronegativity-difference. 2- Induce a change in the oxidation-state of 3 Ce- atoms in the topmost-Ce layer.
  10. 10. ● In TM4 /CeO2 (111) the 2D and 3D TM structures have an atomic arrangement due to the interaction with the surface, which electronic LDOS shows TM states hibridized with the O states and also the formation of localized CeIII . ● In TM13 /CeO2 (111) there is a formation of a pyramid-like structure with a TM/TM4 /TM8 /CeO2 (111) stacking in which the charges flow from the TM8 -layer to the CeO2 (111) surface and the effective- cationic-charge change in 3 Ce-atoms. Conclusions
  11. 11. Publications ● P. Tereshchuk, R.L.H. Freire, C.G. Ungureanu, Y. Seminovski, A. Kiejna, J.L.F. Da Silva, Phys. Chem. Chem. Phys. (2015) DOI: 10.1039/C4CP06016D ● A.S. Chaves, G.G. Rondina, M.J. Piotrowski, J.L.F. Da Silva, Computational Materials Science 98 (2015) 278. ● P. Tereshchuk, M.J.Piotrowski, J.L.F. Da Silva, RSC Advances 5 (2015) 521. ● F.P. Sabino, L.N. de Oliveira, J.L.F. Da Silva, Physical Review B 90 (15) (2014) 155206. ● A.S. Chaves, G.G. Rondina, M.J. Piotrowski, P. Tereshchuk, J.L.F. Da Silva, The Journal of Physical Chemistry A 118 (2014) 10813. ● M.J. Piotrowski, P. Tereshchuk, J.L.F. Da Silva, The Journal of Physical Chemistry C 118 (2014) 21438. ● R.L.H. Freire, A. Kiejna, J.L.F. Da Silva, The Journal of Physical Chemistry C 118 (2014) 19051. ● P. Tereshchuk, A.S. Chaves, J.L.F. Da Silva, The Journal of Physical Chemistry C 118 (2014) 15251. ● P. Tereshchuk, R.L.H. Freire, J.L.F. Da Silva, RSC Advances 4 (2014) 9247. using local, LCCA, and blue-gene resources Thank you! from 2014 and up to now 9 publications

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