Hiroyuki Teramae

Ab initio studies on the geometrical and vibrational structures of polymers

The geometrical structures and vibrational spectra of all‐trans, cis‐transoid and trans‐cisoid polyacetylene, and all‐trans‐polymethineimine have been calculated using the energy gradient scheme for one‐dimensional polymers based on the ab initio crystal orbital method. The vibrational spectra of all‐trans‐polyacetylene reported here are in good agreement with the experimental results. We have proposed a reassignment of the Raman spectra of cis‐transoid‐ polyacetylene. The vibrational spectra of the trans‐cisoid polyacetylene are calculated theoretically. The bond alternant structure of all‐trans‐polymethineimine is more stable than the equidistant one, and the vibrational spectra are calculated for this structure.

The electronic structures of cis-polyacetylene

Abstract The electronic structures of two possible forms of the so-called cis -skeletal polyacetylene ( cis -polyacetylene) are investigated on the basis of the tight-binding LCAO-SCF-MO method under the CNDO/2 version. The analyses of the total energies per unit cell, the π bond orders and the interatomic interaction energies as to the both forms predict the cis -transoid backbone for the cis -polyacetylene. The examination of the patterns of particular molecular orbitals of the hypothetical cis -polymer with equal C-C bond lengths also supports the cis -transoid form.

The electronic structures of fluorinated polyacetylenes. A design of new organic polymer alternatives to polyacetylene

Abstract The electronic structures of polyfluoroacetylene and polydifluoroacetylene are discussed on the basis of the tight-binding LCAO-SCF-MO calculations under the CNDO/2 approximations. A method of preparation of these polymers is also proposed. If they can be successfully prepared, they will be promising candidates for new electric conducting materials as alternatives to polyacetylene.

Electronic properties of pure and doped polyacetylenes

The electronic properties of pure polyacetylene have been studied on the basis of the one-dimensional tight-binding LCAO-SCF-MO calculations. It is deduced that the sudden occurrence of high electrical conductivity in polyacetylenes doped with electron donors or acceptors is essentially brought about by the transfer of an electron from the highest occupied band ( pi ) or to the lowest unoccupied band ( pi *) of the parent polyacetylene.

Energy gradient in the ab initio Hartree—Fock crystal-orbital formalism of one-dimensional infinite polymers

Abstract Energy gradient formulae for one-dimensional polymers are derived using the ab initio Hartree—Fock crystal-orbital formalism. Geometry optimization and vibrational analysis of all-trans polyethylene are performed. The results are in reasonable agreement with experimental values.

Ab initio effective core potential studies on polymers

AbstractAb initio crystal orbital calculation with the effective core potential (ECP) approximation is performed on infinite poly-yne, all-trans-polyethylene, and all-trans-polysilane. The optimized bond lengths of poly-yne are predicted to be 1.130 Å and 1.321 Å with the split valence LP-31G basis set and agree fairly well with 4-31G results, 1.166 Å and 1.339 Å.The energy band structures of poly-yne and all-trans-polyethylene obtained from ECP calculations are in reasonable agreement with those from the all electron calculations. The fully optimized geometries of all-trans-polysilane are also predicted with the LP-31G basis set asrSiSi = 2.264 Å,rSiH = 1.493 Å,

MO study of counter anions of TMTSF: Electronic structure of NO−3, BF−4, ClO−4 and FSO−3

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Theoretical study on gauche-kink in polysilane polymer

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