Jun-ichi Yamamoto - Academia.edu (original) (raw)

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Papers by Jun-ichi Yamamoto

We call this sequence a dynamical system generated by f and denote by qj the value of q0 = q afte... more We call this sequence a dynamical system generated by f and denote by qj the value of q0 = q after j times of the map qj = f (q0). We encounter such systems in various occasion in mathematics, physics and in the nature. All of complex dynamical systems are examples in mathematics. Bäcklund transformations which characterize integrable systems, connection formulae of Stokes geometry E-mail: saito@phys.metro-u.ac.jp The work is supported in part by the Grant-in-Aid for general Scientific Research from the Ministry of Education, Sciences, Sports and Culture, Japan (No 10640278). E-mail: shudo@phys.metro-u.ac.jp E-mail: yjunichi@phys.metro-u.ac.jp E-mail: yoshida@kiso.phys.metro-u.ac.jp

Chem-Bio Informatics Journal, 2014

We have developed a couple of optimal damping algorithms (ODAs) for unrestricted Hartree-Fock (UH... more We have developed a couple of optimal damping algorithms (ODAs) for unrestricted Hartree-Fock (UHF) calculations of open-shell molecular systems. A series of equations were derived for both concurrent and alternate constructions of and Fock matrices in the integral-direct self-consistent-field (SCF) procedure. Several test calculations were performed to check the convergence behaviors. It was shown that the concurrent algorithm provides better performance than does the alternate one.

Journal of Molecular Structure: THEOCHEM, 2010

The production mechanism for interstellar ion HOC þ and its isomer HCO þ from the ion-molecule re... more The production mechanism for interstellar ion HOC þ and its isomer HCO þ from the ion-molecule reaction H 2 O þ C þ was studied using ab initio molecular dynamics. Classical trajectories were calculated by the direct dynamics simulation technique introduced by Takayanagi and Taketsugu (2006) [17] at the B3LYP/ 6-311++G(d,p) level of theory. The accuracy of the B3LYP-level potential-energy surface was checked by comparison with more accurate CCSD-level calculations. More than 200 trajectories were integrated, and it was confirmed that the reaction H 2 O þ C þ mostly produces HOC þ , even though the energy level of HCO þ is lower than that of HOC þ .

Journal of the Physical Society of Japan, 2003

We have proposed, in our previous papers[1, 2], a method to characterize integrable discrete soli... more We have proposed, in our previous papers[1, 2], a method to characterize integrable discrete soliton equations. In this paper we generalize the method further and obtain a q-difference Toda equation, from which we can derive various q-difference soliton equations by reductions.

Computational and Theoretical Chemistry, 2011

The production mechanism for interstellar silicon compounds SiCN, its isomer SiNC, hydrogen cyani... more The production mechanism for interstellar silicon compounds SiCN, its isomer SiNC, hydrogen cyanide HCN and its isomer HNC from the neutral–neutral reactions SiN+CH and SiC+NH was studied using ab initio molecular dynamics. Classical trajectories were calculated by the direct dynamics simulation technique at the B3LYP/6-311++G(d,p) level of theory. Reaction channels were checked by single-point energy calculations on intermediates and transition

Journal of Open Innovation: Technology, Market, and Complexity, 2022

Employee engagement has become a critical issue in Japanese companies. One way to develop it is t... more Employee engagement has become a critical issue in Japanese companies. One way to develop it is to improve the relationship among employees through gratitude expressions. In the post-COVID-19 remote work environment, digital devices are essential. This paper confirms that expressions of gratitude delivered via digital devices enhance the relationship between employees. We experimented in a small-town government office where participants (n = 88) were asked to (1) use the Thanks App, an app we developed to express gratitude, for two months and (2) respond to an engagement survey we developed before and after the experimental period. Through cross-analysis of the data from the app and questionnaire, we found that the “trust in colleagues” factor had a strong correlation (r = 0.80, p < 0.001) with our new index computed by the app’s data. The results suggest that the use of the Thanks App may help visualize the trust relationship among teams. This study has a practical value in prov...

Journal of the Physical Society of Japan, 2004

Journal of Mathematical Physics, 2002

For a given differentiable map (x, y) → (X(x, y), Y (x, y)), which has an inverse, we show that t... more For a given differentiable map (x, y) → (X(x, y), Y (x, y)), which has an inverse, we show that there exists a Hamiltonian flow in which x plays the role of the time variable while y is fixed.

Journal of the Physical Society of Japan, 2001

We propose a method to characterize discrete time evolution equations, which generalize discrete ... more We propose a method to characterize discrete time evolution equations, which generalize discrete time soliton equations, including the q-difference Painlevé IV equations discussed recently by Kajiwara, Noumi and Yamada[1].