主任研究員 触媒機能材料グループ 環境再生材料ユニット 独立行政法人物質・材料研究機構 〒305-0044　茨城県つくば市並木１−１ TEL: 029-860-4547 FAX:029-860-4958 e-mail: UMEZAWA.Naoto[at]nims.go.jp

専門分野

1. Pakpoom Reunchan, Shuxin Ouyang, Naoto Umezawa, Hua Xu, Yuanjian Zhang, and Jinhua Ye,
   “Theoretical design of highly active SrTiO3-based photocatalysts by a codoping scheme towards solar energy utilization for hydrogen production”
   J. Mater. Chem. A, DOI: 10.1039/c2ta00450j
   
   
2. Hua Xu, Pakpoom Reunchan, Shuxin Ouyang, Hua Tong, Naoto Umezawa, Tetsuya Kako, and Jinhua Ye
   “Anatase TiO2 single crystals exposed with high-reactive {111} facets toward efficient H2 evolution”
   Chem. Mater. , DOI: 10.1021/cm303502b
   
   
3. Tetsuya Kako, Naoto Umezawa, Kui Xie, and Jinhua Ye
   “Undoped visible-light-sensitive titania photocatalyst”
   J. Mater. Sci. 48, 108-114, 2013
   
   
4. Naoto Umezawa and Jinhua Ye
   “Role of complex defects in photocatalytic activities of nitrogen-doped anatase TiO₂”
   Phys. Chem. Chem. Phys. 14, 5924-5934, 2012
   
   
5. Shuxin Ouyang, Hua Tong, Naoto Umezawa, Junyu Cao, Peng Li, Yingpu Bi, Yuanjian Zhang, and Jinhua Ye
   “Surface-Alkalinization-Induced Enhancement of Photocatalytic H₂ Evolution over SrTiO₃-Based Photocatalysts”
   J. Am. Chem. Soc. 1341974-1977, 2012
   
   
6. Naoto Umezawa, and Kenji Shiraishi
   “Theoretical model for artificial structure modulation of HfO₂/SiOx/Si interface by deposition of a dopant material”
   Appl. Phys. Lett. 100(9), 092904 (1-4), 2012
   
   
7. Pakpoom Reunchan, Naoto Umezawa, Shuxin Ouyang, and Jinhua Ye
   “Mechanism of photocatalytic activities in Cr-doped SrTiO₃ under visible-light irradiation: an insight from hybrid density-functional calculations”
   Phys. Chem. Chem. Phys. 14, 1876-1880, 2012
   
   
8. Hua Tong, Shuxin Ouyang, Yingpu Bi, Naoto Umezawa, Mitsutake Oshikiri, and Jinhua Ye
   “Nano-photocatalytic Materials: Possibilities and Challenges”
   Adv. Mater. 24, 229-251, 2012
   
   
9. Kui Xie, Naoto Umezawa, Ning Zhang, Pakpoom Reunchan, Yuanjian Zhang, and Jinhua Ye,
   “Self-doped SrTiO_3-δ photocatalyst with enhanced activity for artificial photosynthesis under visible light”
   Energy & Environmental Science 4, 4211-4219, 2011
   
   
10. Katsumasa Kamiya, Naoto Umezawa, and Susumu Okada,
    "Energetics and electronic structure of graphene adsorbed on HfO₂ surface: Density functional theory calculations"
    Phys. Rev. B 83 (15), 153413 (1-4), 2011
    
    
11. Yingpu Bi, Shuxin Ouyang, Naoto Umezawa, Junyu Cao, and Jinhua Ye,
    "Facet effect of single-crystalline Ag₃PO₄ Sub-microcrystals on Photocatalytic Properties"
    J. Am. Chem. Soc. 133 , 6490-6492, 2011
    
    
12. Hua Tong, Naoto Umezawa, Jinhua Ye, and Takahisa Ohno,
    "Electronic coupling assembly of semiconductor nanocrystals: self-narrowed band gap to promise solar energy utilization"
    Energy & Environmental Sci. 4, 1684-1689, 2011
    
    
13. Hua Tong, Naoto Umezawa, and Jinhua Ye,
    "Visible light photoactivity from a bonding assembly of titanium oxide nanocrystals"
    Chem. Commun. 47, 4219-4221, 2011
    
    
14. Naoto Umezawa, Ouyang Shuxin, and Jinhua Ye,
    "Theoretical study of high photocatalytic performance of Ag₃PO₄"
    Phys. Rev. B83(3), 035202 (1-8), 2011
    
    
15. Naoto Umezawa,and Kenji Shiraishi,
    "Origin of high solubility of silicon in La₂O₃: A first-principles study"
    Appl. Phys. Lett. 97(20), 202906 (1-3), 2010
    
    
16. Naoto Umezawa
    "Effects of capping HfO₂ with multivalent oxides toward reducing the number of charged defects"
    Appl. Phys. Lett. 96(2), 162906 (1-3), 2010
    
    
17. Hiroyoshi Momida, Eric Cockayne, Naoto Umezawa, and Takahisa Ohno,
    "Computational study of the dielectric properties of [La, Sc]₂O₃ solid solutions"
    J. Appl. Phys. 107(7), 074104 (1-3), 2010
    
    
18. A. Janotti, J. B. Varley, P. Rinke, N. Umezawa, G. Kresse, and C. G. Van de Walle,
    "Hybrid functional studies of the oxygen vacancy in TiO₂"
    Phys. Rev. B 81(8), 085212 (1-7), 2010
    
    
19. Naoto Umezawa
    "Effects of barium incorporation into HfO₂ gate dielectrics on reduction in charged defects: First-principles study"
    Appl. Phys. Lett. 94(2), 022903(1-3), 2009
    
    
20. Naoto Umezawa, Motoyuki Sato, and Kenji Shiraishi
    "Reduction in charged defects associated with oxygen vacancies in hafnia by magnesium incorporation: First-principles study"
    Appl. Phys. Lett. 93(22), 223104(1-3), 2008
    
    
21. Naoto Umezawa, Kenji Shiraishi, Yasushi Akasaka, Atsushi Oshiyama, Seiji Inumiya, Seiichi Miyazaki, Kenji Ohmori, Toyohiro Chikyow, Takahisa Ohno, Kikuo Yamabe, Yasuo Nara, and Keisaku Yamada
    "Chemical controllability of charge states of nitrogen-related defects in HfO_xN_y: First-principles calculations"
    Phys. Rev. B 77(16), 165130(1-6), 2008
    
    
22. Naoto Umezawa, Anderson Janotti, Patrick Rinke, Toyohiro Chikyow, and Chris G. Van de Walle "Optimizing optical absorption of TiO₂ by alloying with TiS₂"
    Appl. Phys. Lett. 92(4), 041104(1-3), 2008
    
    
23. Naoto Umezawa "Local-density approximation for orbital densities applied to the self-interaction correction"
    J. Chem. Phys. 128(4), 044105(1-8), 2008
    
    
24. Kentaro Doi, Yutaka Mikazuki, Shinya Sugino, Tatsuki Doi, Pawel Szarek, Masato Senami, Kenji Shiraishi, Hiroshi Iwai, Naoto Umezawa, Toyohiro Chikyo, Keisaku Yamada, and Akitomo Tachibana,
    "Electronic Structure Study of Local Dielectric Properties of Lanthanoid Oxide Clusters"
    Jpn. J. Appl. Phys. 47(1), 205 - 211, 2008
    
    
25. Naoto Umezawa, Kenji Shiraishi, Shinya Sugino, Akitomo Tachibana, Kenji Ohmori, Kuniyuki Kakushima, Hiroshi Iwai, Toyohiro Chikyow, Takahisa Ohno, Yasuo Nara, and Keisaku Yamada,
    "Suppression of oxygen vacancy formation in Hf-based high-k dielectrics by lanthanum incorporation"
    Appl. Phys. Lett. 91(13), 132904(1-3), 2007
    
    
26. Naoto Umezawa, Kenji Shiraishi, Seiichi Miyazaki, Takahisa Ohno, Toyohiro Chikyow, Keisaku Yamada, and Yasuo Nara,
    "Hafnium 4f Core-level Shifts Caused by the Nitrogen Incorporation in Hf-based High-k Gate Dielectrics"
    Jpn. J. Appl. Phys. 46(6A), 3507-3509, 2007
    
    
27. Naoto Umezawa, Rajiv K. Kalia, Aiichiro Nakano, Priya Vashishta, and Fuyuki Shimojo,
    "RDX (1,3,5-trinitro-1,3,5-triazine) Decomposition and Chemisorption on Al(111) surface: First-principles molecular dynamics study"
    J. Chem. Phys. 126(23), 234702(1-7), 2007
    
    
28. Naoto Umezawa, Kenji Shiraishi, Kazuyoshi Torii, Mauro Boero, Toyohiro Chikyow, Heiji Watanabe, Kikuo Yamabe, Takahisa Ohno, Keisaku Yamada, and Yasuo Nara,
    "Role of Nitrogen Atoms in Reduction of Electron Charge Traps in Hf-based High-k Dielectrics"
    IEEE Electron Device Lett. 28(5), 363-365, 2007
    
    
29. Akira Uedono, Tatsuya Naito, Takashi Otsuka, Kenichi Ito, Kenji Shiraishi, Kikuo Yamabe, Seiichi Miyazaki, Heiji Watanabe, Naoto Umezawa, Toyohiro Chikyow, Toshiyuki Ohhdaira, Ryuichi Suzuki, Yasushi Akasaka, Satoshi Kamiyama, Yasuo Nara, and Keisaku Yamada,
    "Characterization of Metal/High-k Structures Using Monoenergetic Positron Beams"
    Jpn. J. Appl. Phys. 46(5B), 3214-3218, 2007
    
    
30. Rajendra Prasad, Naoto Umezawa, Dominik Domin, Romelia Salomon-Ferrer, and William A. Lester, Jr.,
    "Quantum Monte Carlo study of first-row atoms using transcorrelated variational Monte Carlo trial functions"
    J. Chem. Phys. 126(16), 164109(1-5), 2007
    
    
31. Yasushi Akasaka, Genji Nakamura, Kenji Shiraishi, Naoto Umezawa, Kikuo Yamabe, Osamu Ogawa, Myoungbum Lee, Toshio Amiaka, Tooru Kasuya, Heiji Watanabe, Toyohiro Chikyow, Fumio Ootsuka, Yasuo Nara, and Kunio Nakamura,
    "Modified Oxygen Vacancy Induced Fermi Level Pinning Model Extendable to P-Metal Pinning"
    Jpn. J. Appl. Phys. 45(49), L128-L1292, 2006
    
    
32. Naoto Umezawa,
    "Explicit Density Functional Exchange Potential with Correct Asymptotic Behavior"
    Phys. Rev. A 74(3), 032505(1-7), 2006
    
    
33. A. Uedono, T. Naito, T. Otsuka, K. Shiraishi, K. Yamabe, S. Miyazaki, H. Watanabe, N. Umezawa, T. Chikyow, Y. Akasaka, S. Kamiyama, Y. Nara, and K. Yamada,
    "Introduction of defects into HfO₂ gate dielectrics by metal-gate deposition studied using x-ray photoelectron spectroscopy and positron annihilation"
    J. Appl. Phys. 100(6), 064501(1-5), 2006
    
    
34. Naoto Umezawa and Toyohiro Chikyow,
    "Orbital-dependent nonlocal correlation energy functional constructed from a Jastrow function: application to atoms and ions"
    Phys. Rev. A 73(6), 062116(1-8), 2006
    
    
35. Naoto Umezawa and Toyohiro Chikyow,
    "Role of the One-body Jastrow Factor in the Transcorrelated Self-consistent-field Equation"
    Int. J. Quantum Chem. 106(7), 1477-1486, 2006
    
    
36. Hiroyoshi Momida, Tomoyuki Hamada, Takenori Yamamoto, Tsuyoshi Uda, Naoto Umezawa, Toyohiro Chikyow, Kenji Shiraishi, and Takahisa Ohno,
    "Effect of nitrogen atom doping on dielectric constants of Hf-based gate oxides"
    Appl. Phys. Lett. 88(11), 112903(1-3), 2006
    
    
37. A. Uedono, K. Ikeuchi, T. Otsuka, K. Shiraishi, K. Yamabe, S. Miyazaki, N. Umezawa, A. Hamid, T. Chikyow, T. Ohdaira, M. Muramatsu, R. Suzuki, S. Inumiya, S. Kamiyama, Y. Akasaka, and Y. Nara, and K. Yamada.
    "Characterization of HfSiON gate dielectrics using monoenergetic positron beams"
    J. Appl. Phys. 99(5), 054507(1-6), 2006
    
    
38. Naoro Umezawa, Antonio Sarsa, Claude Le Sesh, and Toyohiro Chikyow,
    "Determination of simple correlated wave function for few-electron systems using a Jastrow factor"
    Phys. Rev. A 73(1), 012512(1-5), 2006
    
    
39. Heiji Watanabe, Satoshi Kamiyama, Naoto Umezawa, Kenji Shiraishi,
    Shiniti Yoshida, Yasumasa Watanabe, Tsunetoshi Arikado, Toyohiro Chikyow, Keisaku Yamada, and Kiyoshi Yasutake, "Role of nitrogen incorporation into Hf-based high-k gate dielectrics for termination of local current leakage paths"
    Jpn. J. Appl. Phys. 44(43), L1333-L1336, 2005
    
    
40. Naoto Umezawa, Shinji Tsuneyuki, Takahisa Ohno, Kenji Shiraishi, and Toyohiro Chikyow,
    "A practical treatment for the three-body interactions in the transcorrelated variational Monte Carlo Method: application to atoms from lithium to neon"
    J. Chem. Phys. 122(22), 224101(1-9), 2005
    
    
41. Naoto Umezawa, Kenji Shiraishi, Takahisa Ohno, Heiji Watanabe, Toyohiro Chikyow, Kazuyoshi Torii, Kikuo Yamabe, Keisaku Yamada, Hiroshi Kitajima, and Tsunetoshi Arikado,
    "First-Principles Studies of the Intrinsic Effect of Nitrogen Atoms on Reduction in Gate Leakage Current through Hf-based High-k Dielectrics"
    Appl. Phys. Lett. 86(14), 143507(1-3), 2005
    
    
42. Naoto Umezawa and Shinji Tsuneyuki,
    "Excited electronic state calculations by the transcorrelated variational Monte Carlo method: Application to a helium atom"
    J. Chem. Phys. 121(15), 7070-7075, 2004
    
    
43. Naoto Umezawa and Shinji Tsuneyuki,
    "Ground-state correlation energy for the homogeneous electron gas calculated by the transcorrelated method"
    Phys. Rev. B 69(16), 165102(1-6), 2004
    
    
44. Naoto Umezawa and Shinji Tsuneyuki,
    "Transcorrelated method for electronic systems coupled with variational Monte Carlo calculation"
    J. Chem. Phys. 119(19), 10015-10031, 2003