[Pw_forum] For INPUT of WanT

[Andrea Ferretti]

On Mon, 16 Jan 2006, yuss wrote:

> Dear all:
>      Who could offer the example of transport for CNT ( INPUT of PWSCF and WanT)?
>      Thanks 
>       S.S.YU


Hi,

I have no pre-defined input files for transport in C nanotubes (CNT, 
isn't?), but I think you can try to set up the whole transport calculation 
following some of the tests (test06 to test11) provided with WanT.

the needed calculations are:

* pw.x: scf (as usual) and nscf (in order to compute eigenvalues on a 
  regular grid spanning the whole BZ)...
  at the end run pw_export.x to export espresso data 
  (if you are using espresso 3.0 it is already 
  there. otherwise read Sec. 3.1 of WanT manual which explains how to get 
  the pw_export utility) 

* you are now in the position to run want. Some examples of 1D transport 
  calculation are in the tests (particularly test10 and test11) and you 
  can first take a look there to understand which calculations you need
  (the conductor cell only, the leads separately etc etc)...

  the part of the want input which is really very system-specific is
  the choice of the "starting wannier centers" giving the initial guess
  for the wannier localization.
  Some criteria to choose these centers are exaplined in Sec. 5.2 
  (troubleshoting, pag 37): usually they are set on the covalent bonds and 
  on the atoms... 
  test03 provides an example on how this works for benzene... the case of 
  nanotubes should not be that different.
  

Andrea
PS: sorry to those espresso users not directly interested... :-)