扶手椅型单壁碳纳米管的理论研究

Theoretical Study of Armchair Single-walled Carbon Nanotubes

用半经验的 AM1和 PM3方法 ,对不同长度的扶手椅型单壁碳纳米管 (3 ,3 )进行了理论研究 .讨论了其几何结构、前线轨道的分布情况和红外光谱 .结果表明 :碳纳米管中的六边形不再像石墨中的六边形 ,而是发生了变形 ;从碳纳米管的中间到两端 ,各层碳原子在前线轨道中的轨道系数的平方和呈现规律性衰减的锯齿状变化 ;用 AM1方法计算得扶手椅型单壁碳纳米管 (3 ,3 )的红外特征吸收波数约在 1 2 90～ 1 645cm- 1之间 .

Armchair single walled carbon nanotubes (3,3) with different lengths were studied by AM1 and PM3 methods. We found that the hexagons in the ASWCNTs are distorted. The sum of the square of the orbital coefficients in one layer of the frontier orbitals decreases in zigzag manner from the middle to the edge of the nanotubes. The characteristic infrared absorptions of (3,3) armchair single walled carbon nanotubes caculated by AM1 method are between the wave number 1 290 and 1 645 cm -1 .