Transmittance!

[yangzw1985]

Hi, everyone! I have carried out the transmission spectra calculation of my two probe model. It is a nanowire. when the wire is contaion 48 atoms or 72 atoms, the transmission spectra is different with the applied voltage of 0V. Under applied voltage (not zero), the current of 48 atoms is larger than 72 atoms.I want to know if the two probe model changed from metal to semi-conductor.Can any one help me to explain the difference?Thanks!

[yangzw1985]

Hi, everyone! I want to know the reason: why no one answer my question? Do I not make myself to be understood clearly?

[Nordland]

If it is a 1D system perfect periodic system ( nanowire ) then there should be no difference between 48 atoms and 72 atoms. If there are soo, it is due to one (or both) issues:
1) Your electrode is too short and should be increased in size.
2) The geometry is not correct and not perfect, and hence the transmission spectrum can depend strongly on the number of atoms in the central region.

If the current is larger for 48 atoms, and for 72 atoms, then you know that your system is not a metallic system ( this is most likely due to one of the two issues listed above ).
You will have this information for certain before you can make any conclusions. In general metallic system should remain metallic, if a bias is applied. However in some semi-metallic systems
it is sometimes seen that applying a bias can make the system appear like a semi conductor.