SiCNT-Fe interface

[suri]

hi

[zh]

You may optimize an interface structure consisting of a SiC CNT and Fe to obtain a reasonable Fe-C or Fe-Si bond length. Without doing any preliminary calculations, it is difficult (or even impossible) to say which values may be reasonable for the Fe-C or Fe-Si bond length in your desired Fe-SiC CNT-Fe system. 

[suri]

hi

[Umberto Martinez]

You need to include a calculator.
In the script generator, just before the OptimizeGeometry block, add a New Calculator and specify one, ATK-DFT for example.

[suri]

hi

[zh]

If you don't study the surface-dependent properties, you could choose the most stable surface of iron, which can be found from literature because it has been well studied in literature.  The choice of SiC CNT depends on the type (zigzag, armchair, or chiral) of SiC CNT that you want to study. If you want to study all of these three types of SiC CNT, you may have to check all of them with Fe.

[suri]

hi

[zh]

Michelle J.S Spencer, Andrew Hung, Ian K Snook, Irene Yarovsky, Density functional theory study of the relaxation and energy of iron surfaces, Surface Science, Volume 513, Issue 2, July 2002, Pages 389–398
http://www.sciencedirect.com/science/article/pii/S0039602802018095

and reference therein.