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 K. Ohno, S. Maeda
 Chem.Phys.Lett.384,277(2004)
 A Scaled Hypersphere Search Method for the Topography of Reaction Pathways on the 
 Potential Energy Surface
  An algorithm for finding pathways to transition states (TS) or dissociation channels
 (DC) from equilibrium structures (EQ) on the potnetial energy surface (PES) is 
 presented. The pathways around an EQ can be discovered at minima on the scaled 
 hypersphere which would have a constant energy when the potnetials are harmonic. 
 Topographic maps including all TS, DC, and EQ were obtained for ab initio PES of 
 H2O and HCHO in the MP2/3-21G level. The present scaled hypersphere search technique
 in conbination with a downhill-walk algorithm enables us to make a topographic 
 analysis of the PES for a given chemical composition.
 
 S. Maeda, K. Ohno
 J.Phys.Chem.A 109,5742(2005)
 Global Mapping of Equilibrium and Transition Structures on Potnential Energy Surfaces by
 the Scaled Hypersphere Search Method: Applications to ab initio Surfaces of Formaldehyde and 
 Propyne Molecules
  Technical details of a new global mapping technique for finding equilibrium (EQ) and 
 transition structures (TS) on potential energy surfaces (PES), the scaled hypersphere search 
 (SHS) method (Ohno, K.; Maeda, S. Chem. Phys. Lett. 2004, 384, 277), are presented. On the 
 basis of a simple principle that reaction pathways are found as an anharmonic dowward 
 distortion of PES around an EQ point, the reaction pathways can be obtained as energy minimua 
 on the scaled hypersphere surface, which would have a constant energy when the potentials are 
 harmonic. Connections of SHS paths between each EQ are very similar to corresponding intrinsic 
 reaction coordinate (IRC) connections. The energy maximamum along the SHS path reaches a region
 in close proximity to the TS of the reaction pathway, and the subsequent geometry optimization 
 from the SHS maximum structure easily converges to the TS. The SHS method, using the 
 one-after-another algorithm connecting EQ and TS, considerably reduces the multidimensional 
 space to be seaerched to ceartain limited regions around the pathways connecting each EQ with 
 the neighboring TS. Application of the SHS method have beeen made to ab initio surfaces of 
 formaldehyde and propyne molecules to obtain systematically five EQ and nine TS for 
 formaldehyde abd seven EQ and 32 TS for propyene.
 
 K. Ohno, S. Maeda
 J.Phys.Chem.A 110,8933(2006)
 Global Reaction Route Mapping on Potnential Energy Surfaces of Formaldehyde, Formic Acid, and 
 Their Metal-Substituted Analogues
  Global reaction route mapping of equlibrium structures, transition structures, and their 
 connections on potential energy surfaces (PES) have been done for MCHO (M = H, Li, Na, Al, Cu) 
 and HCO2M (M = H, Li). A one-after-another technique based on the scaled hypersphere search 
 method has been successively applied to exploring unknown chemical structures, transition 
 structures, and reaction pathways for organometallic systems. Upon metal substitution,
 considerable changes of stable structures, reaction pathways, and relative heights of 
 transition structures have been discovered, though some features are simlilar, especially 
 around the structures where the Li atom is not directly connected with the methyl group, 
 which indicates little effects of alkyl substitution on the reaction route topology. 
 
 K. Ohno, H. Mutoh, Y. Harada
 J.Am.Chem.Soc.105,4555(1983)
 Study of Electron Distributions of Molecular Orbitals by Penning Ionization 
 Electron Spectroscopy
  Penning ionization electron spectroscopy (PIES) has been used to study spatial
 electron distributions of individual molecular orbitals. On the basis of 
 comparison of observed band intensities with electron densities of ab initio 
 molecular orbitals, a simple principle for orbital activities in Penning 
 ionization has been established; the outer orbital which is exposed outside 
 the van der Waals surface is active and the inner orbital which is localized 
 inside the van der Waals surface is inactive.
  Penning ionization can be considered as an electrophilic reactions of rare 
 gas atoms in metastable states with sample molecules. It is concluded that 
 PIES is a sensitive metohd for probing orbital electron densities at the very 
 frontier of the molecule where the molecule is attacked by the reagent.
 
 K. Ohno, T. Takami, K. Mitsuke, T. Ishida
 J.Chem.Phys.94,2675(1991)
 State-Resolved Collision Energy Dependence of Penning Ionization Cross 
 Sections for N2 and CO2 by He*23S
  The state-resolved collision-energy dependence of Penning ionization cross 
 sections were measured in an energy range (60 < E < 400 meV) for N2 and
 CO2 with He*23S by using a very high-intensity He* beam and
 detecting energy analyzed electrons as functions of time-of-flight of He*.
  The partial ionization cross sections for Π states were observed to increase 
 more rapidly with the increase of the collision energy than those for Σ states. 
 In the studied energy range, the repulsive walls for end-on collisions were 
 indicated to be harder than those for side-on collisions. The directional 
 peculiarity of the potential surfaces was related to the anisotropy in the 
 hybridization of He* orbitals interacting with the target molecules.
 
 K. Mitsuke, T. Takami, K. Ohno
 J.Chem.Phys.91,1618(1989)
 Kinetic Energy Dependence of Partial Cross Sections for the Collisional 
 Ionization of H2O, H2S, and Ar with He*23S Metastable Atoms
 
 K. Ohno, S. Matsumoto, Y. Harada
 J.Chem.Phys.81,4447(1984)
 Exterior Electron Model for Penning Ionization. Unsaturate Hydrocarbonds
  A simple theoretical model is described for Pening ionization (M + A* - 
 M++A+e- in which a metastable-state rare gas atom (A*) extracts
 an electron from a target molecule (M) and ejects another elecron into a 
 continuum state. One of the most importnat factors governing Penning 
 ionization is electron distributions of molecular orbitals which are directly 
 connected with the electronic transition probabilities. 
  Another key factor is the repulsive molecular surafce which divides the 
 unreactive electron densities in the interior region from the reactive electron 
 densities in the exterior region, because the metastable atom A* cannot penetrate 
 into the interior region. In the present model, exterior electron densities (EED) 
 for individual molecular orbitals are considered to be proportional to Penning 
 ionization branching ratios. 
  Good agreements between ab initio MO calculations of EED's and experimental 
 branching ratios of Penning ionization were obtained for various unsaturated 
 hydrocarbon molecules.
 
 Y. Harada, K. Ohno, H. Mutoh
 J.Chem.Phys.79,3251(1983)
 Penning Ionization Electron Spectroscopy of CO and Fe(CO)5. Study 
 of Electronic Structure of Fe(CO)5 from Electron Distribution of
 Individual Molecular Orbitals
 
 T. Takami, K. Mitsuke, K. Ohno
 J.Chem.Phys.95,918(1991)
 Penning Ionization of (CH3)4C and (CH3)sCCl 
 by Collision with He*(23S) Metastable Atom
 
 K. Ohno
 J.Mol.Spectrosc.77,329(1979)
 Normal Coordinate Calculations of Benzenoid Hydrocarbons. Classification 
 and Characterization of Aromatic Planar Vibrations in Polyacenes
 
 T. Takami, K. Ohno
 J.Chem.Phys.96,6253(1992)
 Collision Energy-Resolved Penning Ionization Electron Spectra of Unsaturated 
 Hydrocarbons with He*(23S) Metasatble Atoms
 
 Y. Harada, H. Ozaki, K. Ohno
 Phys.Rev.Lett.52,2269(1984)
 Selective Observation of Outermost Surface Layer during Epitaxial Growth by 
 Penning Ionization Electron Spectroscopy: Pentancene on Graphite.
 
 T. Munakata, K. Ohno, Y. Harada
 J.Chem.Phys.72,2880(1980)
 Application of Penning Ionization Electron spectroscopy to the Study of 
 the Outermost Layer of the Solid Surface
 
 K. Ohno, S. Matsumoto, K. Imai, Y. Harada
 J.Phys.Chem.88,206(1984)
 Penning Ionization Electron Spectroscopy of Nitriles
 
 K. Ohno, H. Yamakado, T. Ogawa, T. Yamata
 J.Chem.Phys.105,7536(1996)
 Collision-Eenergy/Electron-Energy Resolved Two-Dimensional Study of Penning 
 Ionization of Ar by He metastable atoms 23S and 21S
 
 N. Kishimoto, J. Aizawa, H. Yamakado, K. Ohno
 J.Phys.Chem.101,5038(1997)
 Collision-Energy-Resolved Penning Ionization Electron Spectroscopy of Nitriles: 
 Conjugation Effects on Interactions with He*(23S) Metastable Atoms
 
 K. Ohno
 J.Mol.Spectrosc.72,329(1978)
 Normal Coordinate Calculations of Benzenoid Hydrocarbons. 
 Theoretical Models of Simplified Valence Force Fields
 
 S. Maeda, K. Ohno, K. Morokuma
 Phys. Chem. Chem. Phys.15,3683(2013)
 Systemtic Exploration of the Mechanism of Chemical Reactions: Global Reaction Route
 Mapping (GRRM) Strategy by the ADDF and AFIR metohds 
 
 H. Shinohara, Y. Yamakita, K. Ohno
 J.Mol.St.442,221(1998)
 Raman Spectra of Polycyclic Aromatic Hydrocarbons. Comparison of Calculated Raman Intensity
 Distributions with Observed Spectra for Naphthalene, Anthracene, Pyrenen, and Perylene
 
 S. Maeda, K. Ohno
 J. Phys. Chem. A 111,4527(2007)
 Structures of Water Octamers (H2O)8: Exploration on Ab Initio Potential Energy Surfaces
 by the Scaled Hypersphere Search Method
 
 Y. Luo, K. Ohno
 Organometallics 26,3597(2007)
 Computational Study of Titanocene-Catalyzed Dehydrocouping of the Adduct Me2NH-BH3:
 An Intramolecular Stepwise Mechanism 
 
 S. Maeda, K. Ohno, K. Morokuma
 J. Chem. Theory Comput. 6,1538(2010)
 Updated Branching Plane for Finding Conical Intersections without Coupling Derivative
 Vectors
 
 S. Maeda, K. Ohno, K. Morokuma, 
 J. Phys. Chem. A 113,521(2009)
 Automated Global Mapping of Minimum Energy Points on Seams of Crossing by the Anharmonic
 Downward Distortion Following Method: A Case Study of H2CO
 
 Y. Luo, S. Maeda, K. Ohno
 Chem. Phys. Lett. 469,57(2009)
 Water-Catalyzed Gas-Phase Reaction of Formic Acid with Hydroxyl Radical:
 A Computational Investigation
 
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