CMS seminar2011
The thermochemistry of oxidative dehydrogenation of a water molecule at a TiO2/water interface
Prof. Michiel Sprik
【Date & Time】09 September 2011 (Fri), 3:30 pm - 4:15 pm
【Place】4F seminar room(#431-2), MANA Bldg. Namiki site
【Speaker】Professor Michiel Sprik
【Affiliation】Department of Chemistry, University of Cambridge
【Title】The thermochemistry of oxidative dehydrogenation of a water molecule at a TiO2/water interface
【Abstract】
The standard potential vs the normal hydrogen electrode for oxidative dehydrogenation (ODH) of H2O is 2.7V. One might hope that electrocatalysts for oxidation, such as transition metal oxides, can bring this energy down. We have investigated this question for a water molecule adsorbed on the rutile TiO2 (111) surface using Density Functional Theory based Molecular Dynamics (DFTMD) methods. A first challenge in this computation is to check that the method can reproduce the ODH potential in bulk water. Exploiting the latest advances in the CP2K (cp2k.berlios.de), we find 2.5V, encouragingly close to the target value of 2.7V. Adsorption on the TiO2/water interface reduces the ODH potential to 2.0V. However, resolving the dehydrogenation in an acid dissociation and oxidation of the hydroxide anion, it appears that most of this the 0.5 eV activation by the surface is due to an increase in acidity. After outlining the DFTMD method, we will make an attempt in this talk to give an explanation for these observations. This work is in collaboration with Dr. Jun Cheng.
【Contact】Dr. Yoshitaka Tateyama
【Place】4F seminar room(#431-2), MANA Bldg. Namiki site
【Speaker】Professor Michiel Sprik
【Affiliation】Department of Chemistry, University of Cambridge
【Title】The thermochemistry of oxidative dehydrogenation of a water molecule at a TiO2/water interface
【Abstract】
The standard potential vs the normal hydrogen electrode for oxidative dehydrogenation (ODH) of H2O is 2.7V. One might hope that electrocatalysts for oxidation, such as transition metal oxides, can bring this energy down. We have investigated this question for a water molecule adsorbed on the rutile TiO2 (111) surface using Density Functional Theory based Molecular Dynamics (DFTMD) methods. A first challenge in this computation is to check that the method can reproduce the ODH potential in bulk water. Exploiting the latest advances in the CP2K (cp2k.berlios.de), we find 2.5V, encouragingly close to the target value of 2.7V. Adsorption on the TiO2/water interface reduces the ODH potential to 2.0V. However, resolving the dehydrogenation in an acid dissociation and oxidation of the hydroxide anion, it appears that most of this the 0.5 eV activation by the surface is due to an increase in acidity. After outlining the DFTMD method, we will make an attempt in this talk to give an explanation for these observations. This work is in collaboration with Dr. Jun Cheng.
【Contact】Dr. Yoshitaka Tateyama
Electron and Proton Transfer Reactions in Condensed Phase
: Theoretical and Computational Study
Prof. Koji Ando
【Date & Time】21 July 2011 (Thu), 15:30 - 17:00
【Place】4F seminar room (#431-2), MANA Bldg., Namiki site
【Speaker】Prof. Koji Ando
【Affiliation】Dept. of Chemistry, Kyoto University
【Title】Electron and Proton Transfer Reactions in Condensed Phase: Theoretical and Computational Study
【Abstract】
Electron and proton transfers are fundamental and ubiquitous in chemistry and biochemistry. In particular, they play key roles in biological energy conversion processes such as photosynthesis and respiration. Their theoretical and computational modelin at realistic molecular level is, however, still posing a challenge due to their quantum mechanical nature and strong electrostatic coupling to the complex environment This talk will present our recent research on these subjects. For proton transfers, a semiquantal time-dependent Hartree method has been developed and applied to simple model systems, and now being implemented into molecular dynamics simulation Furthermore, although still in embryo, the method has been extended recently to many-fermion systems by exploiting the perfect-pairing valence-bond theory. For electron transfers, we have found that a combination of fragment molecular orbital and tunneling current methods provides an accurate and efficient tool for elucidating the long-distance electron transfer pathways.
【Contact】Dr. Yoshitaka Tateyama
【Place】4F seminar room (#431-2), MANA Bldg., Namiki site
【Speaker】Prof. Koji Ando
【Affiliation】Dept. of Chemistry, Kyoto University
【Title】Electron and Proton Transfer Reactions in Condensed Phase: Theoretical and Computational Study
【Abstract】
Electron and proton transfers are fundamental and ubiquitous in chemistry and biochemistry. In particular, they play key roles in biological energy conversion processes such as photosynthesis and respiration. Their theoretical and computational modelin at realistic molecular level is, however, still posing a challenge due to their quantum mechanical nature and strong electrostatic coupling to the complex environment This talk will present our recent research on these subjects. For proton transfers, a semiquantal time-dependent Hartree method has been developed and applied to simple model systems, and now being implemented into molecular dynamics simulation Furthermore, although still in embryo, the method has been extended recently to many-fermion systems by exploiting the perfect-pairing valence-bond theory. For electron transfers, we have found that a combination of fragment molecular orbital and tunneling current methods provides an accurate and efficient tool for elucidating the long-distance electron transfer pathways.
【Contact】Dr. Yoshitaka Tateyama
Structure and dynamics of water, electrolyte solution and solid/liquid interfaces
- a molecular simulation study -
Prof. Kazuto Akagi
【Date & Time】11 March 2011 (Fri), 16:15 - 17:00
【Place】4F seminar room (#431-2), MANA Bldg., Namiki site
【Speaker】Prof. Kazuto Akagi
【Affiliation】WPI-AIMR, Tohoku University
【Title】Structure and dynamics of water, electrolyte solution and solid/liquid interfaces - a molecular simulation study -
【Abstract】
The microscopic understanding of solid/liquid interfaces leads to the macroscopic understanding of physical and chemical properties, such as friction, lubrication, the power density of batteries and the activity of catalysis. However, several important problems remain to be solved before a discussion can begin on such interface-related phenomena. For example, we have not obtained enough knowledge of the so-called 'structuring of water' at the interfacial region nor a microscopic picture of a bulk electrolyte solution. In this talk, structure and dynamics of bulk pure water, a few types of electrolyte solutions, and simple solid/liquid interfaces will be revealed based on combination of the first-principles and classical molecular dynamics simulations. In order to discuss the higher-order structure of a hydrogen-bond network, an analysis method focusing on the ring-shape structure of hydrogen bonds will also be proposed.
【Contact】Dr. Yoshitaka Tateyama
【Place】4F seminar room (#431-2), MANA Bldg., Namiki site
【Speaker】Prof. Kazuto Akagi
【Affiliation】WPI-AIMR, Tohoku University
【Title】Structure and dynamics of water, electrolyte solution and solid/liquid interfaces - a molecular simulation study -
【Abstract】
The microscopic understanding of solid/liquid interfaces leads to the macroscopic understanding of physical and chemical properties, such as friction, lubrication, the power density of batteries and the activity of catalysis. However, several important problems remain to be solved before a discussion can begin on such interface-related phenomena. For example, we have not obtained enough knowledge of the so-called 'structuring of water' at the interfacial region nor a microscopic picture of a bulk electrolyte solution. In this talk, structure and dynamics of bulk pure water, a few types of electrolyte solutions, and simple solid/liquid interfaces will be revealed based on combination of the first-principles and classical molecular dynamics simulations. In order to discuss the higher-order structure of a hydrogen-bond network, an analysis method focusing on the ring-shape structure of hydrogen bonds will also be proposed.
【Contact】Dr. Yoshitaka Tateyama
Dual description of image processing by the conformal field theory
Prof. Hiroaki Matsueda
【Date & Time】17 February 2011 (Thu), 11:00 am -
【Place】8F large seminar room, Sengen site
【Speaker】Prof. Hiroaki Matsueda
【Affiliation】Sendai National College of Technology
【Title】Dual description of image processing by the conformal field theory
【Abstract】
I am going to introduce a new class of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence in the superstring theory, which appears in image processing based on the density matrix renormalization group method. We find that the compressibility of an image can be well characterized by the conformal charge and the entropic boundary law of a one-dimensional quantum system dual to the original image. I propose a method for accelerating the compressibility by the multi-scale entanglement renormalization. We discuss about the equivalence of images and gravitational fields from the viewpoint of the AdS/CFT correspondence.
【Contact】Dr. Hiroyuki Yamase
【Place】8F large seminar room, Sengen site
【Speaker】Prof. Hiroaki Matsueda
【Affiliation】Sendai National College of Technology
【Title】Dual description of image processing by the conformal field theory
【Abstract】
I am going to introduce a new class of the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence in the superstring theory, which appears in image processing based on the density matrix renormalization group method. We find that the compressibility of an image can be well characterized by the conformal charge and the entropic boundary law of a one-dimensional quantum system dual to the original image. I propose a method for accelerating the compressibility by the multi-scale entanglement renormalization. We discuss about the equivalence of images and gravitational fields from the viewpoint of the AdS/CFT correspondence.
【Contact】Dr. Hiroyuki Yamase
Theoretical Study of Defect induced Electronic and Structural Properties in Perovskite-type Oxides
Mr. Yoshiki IWAZAKI
【Date & Time】3 February 2011 (Thu), 16:00 - 17:00
【Place】4F seminar room (#431-2), MANA Bldg., Namiki site
【Speaker】Mr. Yoshiki IWAZAKI
【Affiliation】Taiyo Yuden Co., Ltd.
【Title】Theoretical Study of Defect induced Electronic and Structural Properties in Perovskite-type Oxides
【Abstract】
Physical properties in perovskite-type ABO3 oxides are well known to be affected by defects and impurities, and the deep understandings of the defect are indispensable for the further improvement of this material. We will discuss the electronic structure of donor-type defects (oxygen vacancy) and impurities (hydrogen, substitutional dopants) in ATiO3 (A=Ba, Sr, Ca) based on the DFT calculations. One of the biggest problems in the defect calculations are insufficient treatment of exchange-correlation energy of local density approximation (LDA) to handle with the localized nature of defect states, and improved methods such as LDA+U and hybrid functional are required to eliminate self-interaction effects in LDA. We present some interesting results of our DFT calculations related with defects in perovskite-type oxides, such as stabilization of hydride ion (H–) at oxygen-vacancy site in ATiO3, and carrier induced phase transition of ferroelectric BaTiO3.
【Contact】Dr. Yoshitaka Tateyama
【Place】4F seminar room (#431-2), MANA Bldg., Namiki site
【Speaker】Mr. Yoshiki IWAZAKI
【Affiliation】Taiyo Yuden Co., Ltd.
【Title】Theoretical Study of Defect induced Electronic and Structural Properties in Perovskite-type Oxides
【Abstract】
Physical properties in perovskite-type ABO3 oxides are well known to be affected by defects and impurities, and the deep understandings of the defect are indispensable for the further improvement of this material. We will discuss the electronic structure of donor-type defects (oxygen vacancy) and impurities (hydrogen, substitutional dopants) in ATiO3 (A=Ba, Sr, Ca) based on the DFT calculations. One of the biggest problems in the defect calculations are insufficient treatment of exchange-correlation energy of local density approximation (LDA) to handle with the localized nature of defect states, and improved methods such as LDA+U and hybrid functional are required to eliminate self-interaction effects in LDA. We present some interesting results of our DFT calculations related with defects in perovskite-type oxides, such as stabilization of hydride ion (H–) at oxygen-vacancy site in ATiO3, and carrier induced phase transition of ferroelectric BaTiO3.
【Contact】Dr. Yoshitaka Tateyama