1997 Fiscal Year Final Research Report Summary
Development of ab initio method including solvent effects and applications to chemical reactions in solution
| Project/Area Number |
08640633
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | University of Tsukuba |
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Principal Investigator |
KIKUCHI Osamu University of Tsukuba, Department of Chemistry, Professor, 化学系, 教授 (30015771)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Ohgi Univ.ofTsukuba, Dep.of Chemisty, Associate Professor, 化学系, 講師 (80241785)
MORIHASHI Kenji Univ.ofTsukuba, Dep.of Chemisty, Associate Professor, 化学系, 助教授 (90182261)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Solvent Effects / MC / MO Hybrid Method / Ab Initio Method |
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| Research Abstract |
1) ab initio GB model in which solvent effect is incorporated into ab initio SCF calculations using generalized Born formula was modified was modified by (i) introducing a steric factor which accounts for the exclusion of the solvent shell of an atom in a molecule by the other atoms, and (ii) re-determination of the parameters used to evaluate the atomic radii which are expressed as a function of the atomic charge obtained by Lowdin population analysis. The hydration energies of neutral molecules, cations and anions are calculated semi-quantitatively by new version of the method.
2) The ab initio GB method has been applied successfully to (1) the S_N reaction of the trimethylsulfonium cation with chloride anion, (2) structure and reactivity of ethylenesulfonium ion in hydrolysis of sulfur mustard, (3) structure and reactivity of trihalide anions in solution, and (4) conformational analysis of amino acid zwitterions in aqueous solution.
3) MC/MO hybrid method was applied to elucidate the solvent effect of hyperfine coupling constants of dimethyl nitric oxide radical (DMNO) in several solvents. The configurations of the solvent molecules were selected from the snapshots in the Monte Carlo simulation for the solution and the electronic structure and the hyperfine coupling constat of DMNO were obtained by averaging the results of 300 configurations. It was recognized that the electron transfer occurs between DMNO and H_2O molecules in two directions, form DMNO to H_2O around the N-O group and from H_2O to DMNO around the CH_3 groups. These electron transfers polarize the N-O bond and increase hfcc of the N atom.
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