Journal of Computer Chemistry, Japan
Online ISSN : 1347-3824
Print ISSN : 1347-1767
ISSN-L : 1347-1767
Volume 1, Issue 4
Displaying 1-4 of 4 articles from this issue
General Papers
  • Akira MURAI, Tsuyoshi NAKAJIMA, Norio TAHARA
    Article type: General paper
    2002 Volume 1 Issue 4 Pages 123-128
    Published: 2002
    Released on J-STAGE: May 02, 2003
    JOURNAL FREE ACCESS
    Ozone, made from air or oxygen by electric discharge, is used in a process called ozonation to purify water (by sterilization, bleaching, and deodorization) in a filtration plant. During an experimental study on an ozone storage process using silica gel, we found that ozone desorption from silica gel proceeds under the same temperature and pressure as ozone adsorption. The extra energy is not required for the ozone desorption except for elution by the oxygen gas stream.
    The ozone gas desorbed from silica gel seemed to be different from normal ozone generated by an ozone generator. First, it smelled a little different from the normal one and remained on clothes for a longer time. Second, it seemed to have a higher specific gravity than the normal one, so that it was necessary to set an ozone leak detector lower to the floor to recover its original sensitivity. We thought that the desorbed ozone contained some kinds of ozone cluster.
    By semi-empirical calculations using MOPAC(PM3), we estimated the energy of association between two ozone molecules as approximately 1 kcal/mol, suggesting the formation of ozone clusters. The value was confirmed by ab initio calculations (MP4 and QCISD(T) using 6-311+G(d) basis set) of the same ozone dimer. This confirmation supported the results obtained by MOPAC(PM3) calculations and thus suggested the existence of the ozone cluster, and indicated the usefulness of the MOPAC(PM3) calculations for qualitative studies on systems associated weakly by van der Waals interaction.
    To get experimental evidence for the ozone cluster, we compared the specific gravity of the desorbed ozone from silica gel with that of Freon gas, HFC-125 (MW=120) and showed that it was heavier than the Freon gas. This fact suggests that the desorbed ozone gas contains some ozone cluster (O9 of mass 144). We analyzed the desorbed ozone by GC/MS and found elution peaks of m/e=96 and 144, corresponding to the dimer and trimer of ozone, respectively. These GC/MS data gave further evidence for the existence of ozone clusters. We named the clusters "Kansai Electric Power Composed Ozone-clusters (KEPCO)."
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  • Mikiji SHIGEMATSU, Takayuki KOBAYASHI, Kouzou YOSHITANI, Mitsuhiko TAN ...
    Article type: General paper
    2002 Volume 1 Issue 4 Pages 129-134
    Published: 2002
    Released on J-STAGE: May 02, 2003
    JOURNAL FREE ACCESS
    The conformation of 2, 6-dimethoxyphenol (DMP), especially the solvent effect on the intra-molecular hydrogen bond was computed with semi-empirical molecular orbital calculation, MOPAC2000. In non-polar solvents (gaseous phase and benzene), the phenolic hydrogen oriented toward one of the methoxyl oxygens via an intra-molecular hydrogen bond. In polar solvents (chloroform, acetone and water), the phenolic hydroxyl group was sited between two methoxyl oxygens with balance of weak hydrogen bonds to them. This solvent effect on the optimum conformation was similar to guaiacol analyzed previously, and would be due to the split of the intra-molecular hydrogen bond caused by interaction from polar solvents. The rotational flexibilities of the hydroxyl and two methoxyl groups of DMP were high, because many of the low energy conformations were detected near the optimum conformation. The flexibilities of two methoxyl groups were lower in water than in gaseous phase. The cause may be complex interaction produced by polar solvents to the balance of intra-molecular hydrogen bonds among hydroxyl group and two methoxyl groups.
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  • Takatoshi NAKA, Shigeyoshi YAMAMOTO, Yasuyo HATANO, Masashi YAMADA, Sh ...
    Article type: General paper
    2002 Volume 1 Issue 4 Pages 135-142
    Published: 2002
    Released on J-STAGE: May 02, 2003
    JOURNAL FREE ACCESS
    This paper presents a novel way of visualization of a molecular orbital as a cloud rendered by real-time computer graphics. Manipulation of molecular structure, such as rotating a certain bond, is realized and the change of orbital is observed in real time. The values of orbital function are sampled and represented by voxel data in rendering. Data sets are constructed when a certain atom stays at some position along a moving path, called the key position. Interpolated position's state is also rendered by blending neighboring key position's volume. That process is performed only by using the blending function in the rendering.
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  • Nao HORIMOTO, Susumu NARITA, Tai-ichi SHIBUYA, Tetsuo MORIKAWA
    Article type: General paper
    2002 Volume 1 Issue 4 Pages 143-148
    Published: 2002
    Released on J-STAGE: May 02, 2003
    JOURNAL FREE ACCESS
    A new program has been developed for the efficient calculation of the total number of the Kekulé Structures and Pauling Bond Orders for large-scale conjugated hydrocarbons.
    The basic idea of the program is that the molecule is divided into three parts and the calculations of Kekulé Structures and Pauling Bond Orders are carried out for the divided parts. After these calculations, the results are unified to obtain Kekulé Structures and Pauling Bond Orders for the original system. The results obtained by the present method are the same as those obtained by other methods. The computational time by this method is less than those given by conventional methods.
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