反式聚乙炔链色散关系的维度效应

Dimension effect of the dispersion curve for an optical branch and an acoustic branch in planar trans-polyacetylene

利用经典力学方法研究了二维反式聚乙炔链的光学模和声学模的维度效应。链的二聚化引起系统的对称性降低 ,从而导致光频支格波和声频支格波的宽度 (ω2 + (k =0 ) -ω2 -(k =0 ) )明显变窄 ,而对BZ边界面上两支格波的间隙 (ω2 + (k=π/a) -ω2 -(k =π/a) )

The dimension effect of the dispersion curves of an optical branch and an acoustic branch for a planar trans-polyacetylene chain has been investigated using the classical mechanical method. It is assumed that the angle between two C-C bonds is constant in process of the dimerization of carbon sites. The dimerization makes the symmetry of the system reduce and the width (ω 2 +(k=0)-ω 2 -(k=0)) of both branches decrease obviously, and which nearly hasn't an effect on the gap (ω 2 +(k=π/a)-ω 2 -(k=π/a)) of both branches.