Far- and Mid-Infrared of Crystalline 2,2′-Bithiophene
J. Phys. Chem. A, Vol. 109, No. 8, 2005 1691
(6) Furukawa, Y.; Akimoto, M.; Harada, I. Synth. Met. 1987, 18, 151.
(7) Zerbi, G.; Chierichetti, B.; Inga¨nas, O. J. Chem. Phys. 1991, 94,
have found good agreement between the calculated phonon
frequencies and their experimental values according to the
symmetry properties of the eigenvectors of the dynamical matrix.
The Born effective charges are found to be small which is typical
of a covalently bonded organic system. The traces of the BECTs
indicate that the charges on the hydrogen and sulfur atoms are
positive, whereas the charges on the carbon atoms are negative
except for the carbon atoms included in the intercycle bond,
which are charged positively in the crystalline phase. The good
agreement between the calculated and experimental infrared
spectra allows us to assign the origin of the main features of
the experimental spectra and demonstrates the accuracy of the
BECT calculations. In particular, we have proposed for the first
time an assignment of the vibrational modes in the far-infrared
domain.
In contrast to our previous calculations of the INS spectrum
for the 2T crystalline phase, the simpler infrared spectrum at a
low frequency reveals problems in the precision of the far-
infrared mode calculations, which could be related in part to
the lack of dispersive interactions in the DFT methods but also
to experimental problems during the preparation of 2T samples.
Recently, this work has been extended to longer oligomers,
like R-quaterthiophene and R-sexithiophene, to understand in
detail the experimental results (INS and infrared spectra) of these
materials.
4637.
(8) Hohenberg, P.; Kohn, W. Phys. ReV. 1964, 136, B864.
(9) Kohn, W.; Sham, L. J. Phys. ReV. 1965, 140, A1133.
(10) Parlinski, K. Am. Inst. Phys. Conf. Proc. 1999, 479, 121.
(11) Hermet, P.; Bantignies, J. L.; Rahmani, A.; Sauvajol, J. L.; Johnson,
M. R. J. Phys.: Condens. Matter 2004, 16, 7385.
(12) Socrates, G. Infrared and Raman Characteristic Group Frequencies;
Wiley: Chichester, U.K., 2001.
(13) Kresse, G.; Furthmu¨ller, J. Phys. ReV. B 1996, 54, 11169.
(14) Kresse, G.; Furthmu¨ller, J. Comput. Math. Sci. 1996, 6, 15.
(15) Kresse, G.; Hafner, J. Phys. ReV. B 1993, 47, 558.
(16) Perdew, J. P.; Burke, K.; Ernzerhof, M. Phys. ReV. Lett. 1996, 77,
3865.
(17) Kresse, G.; Joubert, D. Phys. ReV. B 1999, 59, 1758.
(18) Monkhorst, H. J.; Pack, J. D. Phys. ReV. B 1976, 13, 5188.
(19) Parlinski, K. PHONON Software; Cracow, 2001.
(20) King-Smith, R. D.; Vanderbilt, D. Phys. ReV. B 1993, 47, 1651.
(21) Frisch M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, T.; Kudin, K. N.;
Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.;
Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.;
Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels,
A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.;
Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.;
Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz,
P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.;
Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson,
B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03,
revision B.03; Gaussian, Inc.: Pittsburgh, PA, 2003.
Acknowledgment. We are grateful to Martijn Marsman for
the fruitful discussions on Berry’s phase procedure and the
CINES (Montpellier, France) for computational facilities (IBM
SP3 computers were used).
(22) Maradudin, A. A.; Montroll, E. W.; Weiss, G. H.; Ipatova, I. P.
Theory of lattice dynamics in the harmonic approximation; Academic
Press: New York, 1971.
(23) The asterisk superscript of Z/Râ(n) is not the symbol for the
References and Notes
complex conjugation operation. Z/Râ(n) is always a real quantity.
(24) Pelletier, M.; Brisse, F. Acta Crystallogr., Sect. C 1994, 50, 1942.
(25) Louarn, G.; Buisson, J. P.; Lefrant, S.; Fichou, D. J. Phys. Chem.
1995, 99, 11399.
(1) Roncali, J. Chem. ReV. 1992, 92, 711.
(2) Hotta, S.; Hosaka T.; Shimotsuma W. Synth. Met. 1983, 6, 69.
(3) Nalwa, H. S. Handbook of Organic ConductiVe Molecules and
Polymers; Wiley: Chichester, U.K., 1997.
(26) Akimoto, M.; Furukawa, Y.; Takeuchi, H.; Harada, I. Synth. Met.
1986, 15, 353.
(27) Hermet, P.; Bantignies, J. L.; Sauvajol, J. L.; Johnson, M. R.
Manuscript in preparation.
(4) Mu¨llen, K.; Wegner, G. Electronic Materials: The Oligomer
Approach; Wiley-VCH: Weinheim, 1998.
(5) Degli Esposti, A.; Zerbetto, F. J. Phys. Chem. A 1997, 101, 7283.