[DFTB-Plus-User] NEGF: IV curve

[MF]

Thanks, Gabriele! I thought the default units were volts; I must have read the manual incorrectly. Anyway, thanks for pointing that out.

Sent from my iPhone

> On Apr 22, 2015, at 11:56 PM, Gabriele Penazzi <penazzi at uni-bremen.de> wrote:
> 
> Hi Michael,
> 
> the default unit for the bias in the input file is Hartree (we borrow energy units to be consistent with the rest of input), see manual. If you want to apply V you have to specify [eV] after the potential keyword.  Therefore you're applying 0.2H=5.4V, not 0.2V as you think. Considering this, the conductance look fine and you're being able to converge at quite high bias. 
> 
> I don't know what happens at 0.1H, but if you go to quite large bias you should maybe check you're electrostatic (is the device still long enough to let the potential relax correctly) and understand better if you step in some event which may change your device behaviour (e.g. crossing other bands, injecting charge in defect states etc.)
> 
> Best
> Gabriele
> 
> 
> 
> 
>> On 04/23/2015 02:05 AM, Michael Foster wrote:
>> Hi,
>> 
>> I'm trying to predict an IV curve for a 10,10-CNT but the result I'm getting seems a little strange (see Fig. below). Why is the current flatting out and even slightly decreasing as the drain voltage is increased?  For the calculations, the source voltage is constant (0 V) and I'm simply increasing the drain voltage in 0.01 V increments and reading in the previous charge file. The curve starts off as expected, linear (ohmic conduction) but diverges quickly. In addition, I can't get the system to converge with applied voltages larger then ~0.2 V. Any input will be appreciated. Attached is the input file.
>> 
>> Thanks    
>> 
>> <mime-attachment.png>
>> 
>> 
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> -- 
> --
> Dr. Gabriele Penazzi
> BCCMS - University of Bremen
> 
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