Hi all,
As a newbie on using transiesta, I've read through the manual and search
the answer from google, but cann't figure out the following things:
1- Are there some rules for determining the electrode unit cell used in
transiesta? Say, in the following example:
http://wiki.tstutorial.dreamhosters.com/wiki/1D_Si_chain, we can see
that: The two-atom supercell represented the 1D Si chain was elected as
the electrode. Why should they use a two-atom supercell as the
electrode? I mean, why not use the primitive unit cell, or three-atom
supercell, and so on as the electrode for the above example?
2- In this example, we can read the following sentences:
-------------------
Convince yourself that this calculation can be used as electrodes for
TranSIESTA calculations, i.e., check that there are no interactions or
overlaps between next-nearest neighbor cells.
-------------------
How to ensure this?
3- From the following notes
(http://www.icmab.es/siesta/documentation/tutorials/Lyon-2007/TranSIESTA.ppt
, page. 20 ) , I learned that: B (buffer) does not enter directly in
the calculation (only in the SC calc. for V_Hartree). Does this mean
that we should not include the buffer atoms in the PBC supercell for our
transiesta computation, ie., only the atoms belong two electrodes and
central scatter region should be depicted by using fractional or
Cartesian coordinates, in the fdf file?
4- In the above example I mentioned here, I also read the following
sentence:
--------------
Here we are coupling a scattering region of 7 atoms to two electrodes
(left and right) that are semi-infinite representations of the perfect
1D Si wire.
-----------------
What does the `semi-infinite representations' mean? I mean, in this
model, if we repeat the supercell (a scattering region of 7 atoms to two
electrodes) along the chain's direction, we will get the perfect 1D Si
wire. So, why not saying the `infinite representation'? Could you
please give me some hints?
Regards.
--
Hongyi Zhao <[email protected]>
Institute of Semiconductors, Chinese Academy of Sciences
GnuPG DSA: 0xD108493
