### Résumé

polymer (repeating unit -C=N-CH$_3$), whose most stable conformation is

expected to be a helical chain. The computations used a standard contracted Gaussian orbital set at the computational levels STO-3G, 3-21G, 6-31G, and 6-31G$^{**}$, and studies were made for two line-group configurations motivated by earlier work and by studies of space-filling molecular models:

(1) A structure of line-group symmetry $L9_5$, containing a 9-fold screw

axis with atoms displaced in the axial direction by 5/9 times the lattice constant, and (2) A structure of symmetry $L4_1$ that had been proposed, containing a four-fold screw axis with translation by 1/4 of the lattice constant. Full use of the line-group symmetry was employed to cause most of the computational complexity to depend only on the size of the asymmetric repeating unit. Data reported include computed bond properties, atomic charge distribution, longitudinal polarizability, band structure, and the convoluted density of states. Most features of the description were found insensitive to the level of computational approximation. The work also illustrates the importance of exploiting line-group symmetry to extend the range of polymer structural problems that can be treated computationally.

langue | Anglais |
---|---|

Numéro d'article | DOI: 10.1021/acs.jpca.7b07403 |

Pages | 7993-8002 |

Nombre de pages | 10 |

journal | Journal of Physical Chemistry A |

Volume | 121 |

Date de mise en ligne précoce | 13 sept. 2017 |

état | Publié - 13 sept. 2017 |

### mots-clés

### Citer ceci

*Journal of Physical Chemistry A*,

*121*, 7993-8002. [DOI: 10.1021/acs.jpca.7b07403].

}

*Journal of Physical Chemistry A*, VOL. 121, DOI: 10.1021/acs.jpca.7b07403, p. 7993-8002.

**Electronic Band Structure of Helical Polyisocyanides.** / Fripiat, Joseph G.; Champagne, Benoît; Liégeois, Vincent; Harris, Franck E. .

Résultats de recherche: Contribution à un journal/une revue › Article

TY - JOUR

T1 - Electronic Band Structure of Helical Polyisocyanides

AU - Fripiat,Joseph G.

AU - Champagne,Benoît

AU - Liégeois,Vincent

AU - Harris,Franck E.

PY - 2017/9/13

Y1 - 2017/9/13

N2 - Restricted Hartree-Fock computations are reported for a methyl isocyanidepolymer (repeating unit -C=N-CH$_3$), whose most stable conformation isexpected to be a helical chain. The computations used a standard contracted Gaussian orbital set at the computational levels STO-3G, 3-21G, 6-31G, and 6-31G$^{**}$, and studies were made for two line-group configurations motivated by earlier work and by studies of space-filling molecular models:(1) A structure of line-group symmetry $L9_5$, containing a 9-fold screwaxis with atoms displaced in the axial direction by 5/9 times the lattice constant, and (2) A structure of symmetry $L4_1$ that had been proposed, containing a four-fold screw axis with translation by 1/4 of the lattice constant. Full use of the line-group symmetry was employed to cause most of the computational complexity to depend only on the size of the asymmetric repeating unit. Data reported include computed bond properties, atomic charge distribution, longitudinal polarizability, band structure, and the convoluted density of states. Most features of the description were found insensitive to the level of computational approximation. The work also illustrates the importance of exploiting line-group symmetry to extend the range of polymer structural problems that can be treated computationally.

AB - Restricted Hartree-Fock computations are reported for a methyl isocyanidepolymer (repeating unit -C=N-CH$_3$), whose most stable conformation isexpected to be a helical chain. The computations used a standard contracted Gaussian orbital set at the computational levels STO-3G, 3-21G, 6-31G, and 6-31G$^{**}$, and studies were made for two line-group configurations motivated by earlier work and by studies of space-filling molecular models:(1) A structure of line-group symmetry $L9_5$, containing a 9-fold screwaxis with atoms displaced in the axial direction by 5/9 times the lattice constant, and (2) A structure of symmetry $L4_1$ that had been proposed, containing a four-fold screw axis with translation by 1/4 of the lattice constant. Full use of the line-group symmetry was employed to cause most of the computational complexity to depend only on the size of the asymmetric repeating unit. Data reported include computed bond properties, atomic charge distribution, longitudinal polarizability, band structure, and the convoluted density of states. Most features of the description were found insensitive to the level of computational approximation. The work also illustrates the importance of exploiting line-group symmetry to extend the range of polymer structural problems that can be treated computationally.

KW - polyisocyanides

KW - Helical polymer

KW - band structure

KW - Electronic properties

KW - Symmetry

KW - line group

KW - Ewald procedure

KW - Fourier-space LCAO Hartree-Fock

M3 - Article

VL - 121

SP - 7993

EP - 8002

JO - Journal of Physical Chemistry A

T2 - Journal of Physical Chemistry A

JF - Journal of Physical Chemistry A

SN - 1089-5639

M1 - DOI: 10.1021/acs.jpca.7b07403

ER -