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Transferable semiempirical quadratic force fields: The case of polythiophene and shorter oligomers
Author(s) -
Ramírez F. J.,
Hernández V.,
Navarrete J. T. López
Publication year - 1994
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.540150405
Subject(s) - mndo , thiophene , chemistry , computational chemistry , force field (fiction) , raman spectroscopy , molecular physics , monomer , quadratic equation , polythiophene , infrared , infrared spectroscopy , polymer , conductive polymer , molecule , quantum mechanics , physics , organic chemistry , mathematics , geometry
The vibrational spectra of oligomers of thiophene are treated theoretically with the main purpose of deriving information for the interpretation of the infrared and Raman spectra of the polymer and isotopic derivatives. We report the results of a series of semiempirical MNDO calculations on the structure and vibrational properties of oligothiophenes, and we compare the calculated MNDO Pulay scaled force field of the monomer with an empirical harmonic force field that we have obtained by least squares refinement on nine isotopic derivatives. The scaling factors obtained were transferred from thiophene for the computation of the vibrational spectrum and the phonon dispersion curves of the polymer. © 1994 by John Wiley & Sons, Inc.