Ab initio calculations of the ground‐state potential energy surface for the CF bond decomposition in <i>n</i>‐fluoropropane within the method for approximation of the frozen molecular fragment

Theoretical studies on the electronic and the geometrical structures for various molecules by the molecular orbital or the density functional theory have recently been developed and applied widely under the progress of computer technologies. At present, it is possible to carry out a theoretical investigation on electronic properties for small molecules at the Hartree᎐Fock and the post-Hartree᎐Fock levels by the improvement of advanced program packages. However, it is difficult to perform the theoretical calculations on electronic structures for large polymers with the aperiodic sequence of molecular segments, because the theoretical treatment of random systems has not yet been established. We recently proposed the elongation method as a useful theoretical approach to obtain the electronic states of any polymers without the periodic geometry of molecular fragments. In the previous works, the reliability of our treatment has been shown by the application to many polymers under single-point calculations with fixed molecular geometry. Thus, as the next step of our study, an attempt for the geometry optimization of large polymers by the elongation method was made in this work. As the first samples of geometry optimization, the periodic polymers of polyethylene, polyacetylene, and polyglycine were examined. Also, as the second samples, the locally aperiodic polymers of polyacetylene with local defects of positively and negatively charged solitons were tested. Total energies, optimized geometries, and electron densities were checked by those obtained from the conventional molecular orbital method.

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Geometry optimization of polymers by the elongation method

Mitani

Aoki

Imamura

1997

Int J of Quantum Chemistry

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An efficient procedure for calculations of interaction energy in large molecular systems

Roszak¹

1993

Chemical Physics Letters

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Application of the elongation method to the calculation of electronic structures of the interface and the local defect states in a polymer: An analysis of the periodicity in the electronic states of a nonperiodic polymer by using the cluster-series calculation

Mitani

Imamura

1994

The Journal of Chemical Physics

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Articles you may be interested inBand structure of polymer extracted from oligomer calculations by elongation method and its applications to nanosystems AIP Conf.A novel molecular orbital method for the calculations of polymer systems with local aperiodic part: The combination of the elongation method with the supercell method Stationary space analysis of the electronic structure of a polymer system: From cluster model to cluster series model J. Chem. Phys. 98, 7086 (1993); 10.1063/1.465060Local density of states of aperiodic polymers using the localized orbitals from an ab initio elongation methodWe have developed an approach at the Hartree-Fock level by which itis possible to calculate the electronic structures of large polymers with or without periodic sequences systematically. This elongation method is based on the concept of a cluster-series calculation which means the ~ successive connection of cluster molecules at the molecular orbital level in approximating a large_ polymer as a cluster molecule. It has already been reported that we can extract the periodic condition of the electronic states within the series of extended clusters by using the cluster-series model. Recently, we tried to introduce the elongation method into the program package of semiempirical molecular orbital methods MOPAC. In the present paper, we report results of applications to the calculations of three polymer systems by using AMI parameters, that is, the first system is the periodic polymer, the second is the interface between two blocks in a polymer chain, and the third is the local_ defeCt within a periodic polymer. In calculations of periodic polymers, clusters of polyethylene, polytetrafluoroethylene, polyacetylene, or polydifluoroacetylene were elongated in one direction, and the interfaces between the above polymer biocks with ethylene-or acetylene-type chain were dealt with by the two-directional elongation method. Also, the solitonic structures with one plus or minus charge within polyacetylene chain were created in elongation calculations of the bidirectional extension as models for the local defect in a periodic polymer. Moreover, we discussed periodic states-of electronic structures in these systems from cluster-series calculations.7712

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Ab initio calculations of the ground‐state potential energy surface for the CF bond decomposition in n‐fluoropropane within the method for approximation of the frozen molecular fragment

Cited by 4 publications

References 32 publications

Geometry optimization of polymers by the elongation method

Geometry optimization of polymers by the elongation method

An efficient procedure for calculations of interaction energy in large molecular systems

Application of the elongation method to the calculation of electronic structures of the interface and the local defect states in a polymer: An analysis of the periodicity in the electronic states of a nonperiodic polymer by using the cluster-series calculation

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