[DFTB-Plus-User] Carbon nanotube in the dftb+ program

[George D Kubas]

Hello,


I aplogize. I sent the wrong hsd file. My correct file has the geometry section as such.

Transport {
  Geometry {
    Device {
      AtomRange =1 160
    }
    Contact {
      Id = "source"
      AtomRange =161 288
    }
    Contact {
      Id = "drain"
      AtomRange =289 416
    }

  }


The same error persists with this code. I will check out the fortran utility you attached to see if this resolves my problem. Thank you for your help.




________________________________
From: dftb-plus-user-bounces at mailman.zfn.uni-bremen.de <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of Gabriele Penazzi <penazzi at uni-bremen.de>
Sent: Monday, November 23, 2015 10:08 PM
To: dftb-plus-user at mailman.zfn.uni-bremen.de
Subject: Re: [DFTB-Plus-User] Carbon nanotube in the dftb+ program

Hi George,

there is some error in the setup. The unit cell of the CNT is 32 atoms, the contacts must be two identical layers. In your input file the contact has 160 atoms, corresponding to 5 unit cells. Clearly the two layers can not be two rigidly shifted layers because they'd need an even number of unit cells.

The code write out the lattice vector extracted for the contact when there's an error, you see there's some problem because it has a non zero component in the x direction.

There's a tiny fortran utility I sent in mailing list (https://mailman.zfn.uni-bremen.de/pipermail/dftb-plus-user/2015/002008.html) which may help you, it is used to repeat a principal layer N times in a way which satisfies the ordering, see also the online tutorial.

Last, if you can compile it consider to use the MPI version, the input format has changed a bit and the MPI format contains the latest one which we'll try to support now on.

Best,
Gabriele


On 11/23/2015 11:42 PM, George D Kubas wrote:

Hello,


I am quite new to the program and am trying to set up an 8,0 cnt geometry in a .gen file. When I run the dftb+ program on the source contact file I keep getting the error "Contact 1 does not consist of two rigidly shifted layers". I used http://turin.nss.udel.edu/research/tubegenonline.htmlto generate the atomic positions in a Gaussian format and 13 cell units long. I thought I set up the correct order of device, source layer closest to device, source layer furthest, drain layer closest to the device, and drain layer furthest. I assume my error lies in the self created .gen file. Any help would be greatly appreciated. Thank you for your time.



George



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