what is the difference in properties of following two structures

[namrata]

hello everyone
can someone tell me what is the different between following two electrodes
1] the Z-A-Z script electrodes attached [2009.06 version]
2] the electrodes prepared using 2008.10 from graphene nanoribbon script on Quantumwise website

[zh]

When one describes the electrode, he must give the following information:
i) lattice vectors of unit cell: length, angle, and etc;
ii) the number of atoms containing in unit cell;
iii) the atomic species (i.e., electrode_elements);
iv) the atomic coordinates.

So, it is easy to find out the difference in your mentioned two script file.
At least, you can see that the lattice vectors are different:
"zigzag.py"

# Set up lattice
vector_a = [32.09404, 0.0, 0.0]*Angstrom
vector_b = [0.0, 10.0, 0.0]*Angstrom
vector_c = [0.0, 0.0, 9.84400684177]*Angstrom
left_electrode_lattice = UnitCell(vector_a, vector_b, vector_c)

"graphene_ribbon--electrodes.py"

electrode_cell = [[ 43.56888   ,   0.        ,   0.        ],
                  [  0.        ,  43.56888   ,   0.        ],
                  [  0.        ,   0.        ,   9.84400684]]*Angstrom

The striking difference is that the lattice vectors of center region should be defined in the former case, while they are not required to be given in the latter case.

[namrata]

thanks Zh,
but actually i wanted to know what difference it makes if the terminations of right and left electrodes r not identical as in the two geometries i had attached .
because when we use scripting we get identically terminated electrodes but in atomic manipulator it is not so and what difference this makes this i wanted to know .
namrata

[Anders Blom]

I assume you mean the "termination" in the Z direction, because they are identical in the XY directions.

However, what you are forgetting is that the electrodes are not terminated in the transport direction - they extend to infinity. And therefore, they are identical!