掺杂对碳链的输运性质影响的第一性原理研究

Study on First Principles of Effect in the Gas Molecules on the Transport Properties of a Carbon Wire

该文用第一性原理非平衡格林函数方法研究了掺杂对7个碳原子组成的一维原子链的输运性质的影响．碳原子链放在具有有限截面的Al（100）电极中．特别地，我们选取了7种常见的气体分子（H2、O2、CO2、HCl、NO、NO2、SO2）作为研究对象，研究发现，气体分子的介入不但改变了碳链上电荷的分布，而且不同程度地减少了从电极转移到碳链和气体上的电荷数目，对体系输运性质产生很大的影响．特别地：放置H2时，使碳链体系的平衡电导由1．06G0降为1．01C0；而放置S02时，使其平衡电导竞降到了0．1C0.此外，研究放置各种气体分子时，体系的电流．电压（I-V）特性，在0～1．0V的电压范围内．放置NO、HCl、NO2时出现了很大的负微分电阻，而放置O2、CO2时没有出现负微分电阻．

We investigate the effect of adulterant on the transport properties of a seven-atom carbon wire coupled to two Al（100） electrodes based on a recently developed abinitio nonequilibrium Green function formalism. Specially, we choose seven types of usual gas molecules（ H2,O2, CO2, HCL ,NO, NO2, SO2） as examples. Studies show that the interposition of gas molecules have great impact on the transport properties of the system not only altering the charge distribution on the carbon wire but also reducing the charge transfer from the electrode to the central region. Especially, the equilibrium conductance of the system is 1.01 Go when we place gas molecules H2 on the carbon wire., while it decreas-s to 0. 1 Go for gas SO2. The calculated current-voltage curves show strong different behavior with the gas molecules NO, HCl and NO2. but for O2 and CO2, no negative differential resistance （NDR） is found.