Polyyne bending frequencies: why they vary with the square of the harmonic in the infinite limit
Titel:
Polyyne bending frequencies: why they vary with the square of the harmonic in the infinite limit
Auteur:
SEITZ, CHRISTA EAST, ALLAN L. L.
Verschenen in:
Molecular physics
Paginering:
Jaargang 101 (2003) nr. 9 pagina's 1267-1271
Jaar:
2003-05-10
Inhoud:
The vibrational frequencies of several linear polyynes HCNH, HCNI and ICNI, for even-valued N up to 60, have been obtained using computational quantum chemistry. The bending normal modes have the appearance of classical transverse normal modes of a vibrating string fixed at both ends, for which the frequencies vary with the first power of the harmonic. Our calculations, however, reveal that in the limit of infinite chain length and infinite mass on the ends of the 'molecular string', the bending frequencies vary with the square of the harmonic, at all levels of theory. A derivation is presented to explain the discrepancy.
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