Connection among Raman wavenumbers, bond length alternation and energy gap in polyynes

A theoretical model based on Huckel theory is presented and applied to the infinite linear carbon chain. The effect of Peierls distortion, pi-electron confinement and electron-phonon coupling are interpreted on the basis of measurable parameters such as bond length alternation, electronic gap and Raman wavenumbers. A diagram is presented where the correlation among these quantities is shown on the basis of the model adopted. The effect of pi-electron confinement on experimental data can be directly evaluated, and insights on the physical properties of these materials can be derived. Copyright (C) 2009 John Wiley & Sons, Ltd.