When finite becomes infinite: convergence properties of vibrational spectra of oligomer chains

Chien Pin Chou, Henryk Witek, Stephan Irle

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We present a computational study of convergence properties of vibrational IR and Raman spectra for a series of increasingly long units of polyethylene, cis- and trans-polyacetylenes, and polyynes. Convergent behavior to the spectra of infinitely long polymers was observed in all cases when chains reached lengths of approximately 60 carbon atoms, both with respect to the positions of the bands and to their intensities. The vibrational spectra of longer chains are practically indistinguishable. The convergence rate depends on the degree of the π conjugation in a studied system: Vibrational spectra for oligoethylenes converge noticeably faster than the spectra for the conjugated systems. The slowest convergence is observed for skeletal motions of the oligomer chains, which may require more than a hundred carbon atoms in the chain to show deviations smaller than 1 cm−1 to the corresponding solid-state calculations. The results suggest that the boundary between the properties of finite and infinite molecular systems fades away for a surprisingly small number of atoms.

Original languageEnglish
Article number288
JournalJournal of Molecular Modeling
Volume24
Issue number10
DOIs
Publication statusPublished - 2018 Oct 1

Fingerprint

Vibrational spectra
Polyacetylenes
oligomers
Oligomers
vibrational spectra
Atoms
Carbon
Polyethylene
atoms
Chain length
Polyethylenes
Raman scattering
polyacetylene
carbon
Polymers
conjugation
polyethylenes
Raman spectra
solid state
deviation

Keywords

  • Convergence in size evolution
  • SCC-DFTB
  • Simulations of IR and Raman spectra of polymers

ASJC Scopus subject areas

  • Catalysis
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Computational Theory and Mathematics
  • Inorganic Chemistry

Cite this

When finite becomes infinite : convergence properties of vibrational spectra of oligomer chains. / Chou, Chien Pin; Witek, Henryk; Irle, Stephan.

In: Journal of Molecular Modeling, Vol. 24, No. 10, 288, 01.10.2018.

Research output: Contribution to journalArticle

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