Messages

121

General Questions and Answers / Re: how to construct a Titanium electrode

« on: April 29, 2014, 00:32 »

Yes, the cluster model can not be a practice device.

i know. 

thank your for your reply.

122

General Questions and Answers / Re: how to construct a Titanium electrode

« on: April 28, 2014, 23:26 »

Thank you

in fact, i don not understand why the author used the Ti cluster as two electrodes also.

123

General Questions and Answers / Re: how to construct a Titanium electrode

« on: April 23, 2014, 17:09 »

Yes, the Titanium electrode is built following (0001) cristal orientation,
but another question is the electrode is Titanium cluster,

i know in ATK, the electrode can be a period system, so i am wondering whether the cluster can be dealt correcltly?


i need your help!

thanks very much!   

124

General Questions and Answers / two-probe system can deal with the situation in which a cluster as a electrode?

« on: April 22, 2014, 21:52 »

hi,

i want to model the Ti-cluster-GNR-Ti-cluster as which in the reference http://pubs.acs.org/doi/abs/10.1021/nn401357p,see the geometry configuration.
and  i already know each electrode is a period system in ATK, but i do not know if a electrode is a cluster, atk can model the case?

125

General Questions and Answers / how to construct a Titanium electrode

« on: April 22, 2014, 18:42 »

Hi:

i am trying  to construct a Titanium electrode, i am puzzled that when i used a "add"---->"from database", it shows three choice: alfa, beta, omega. so i do not know which to choose? which is often chosen as a electrode? as i know for gold, its (1,1,1) surface is ofter chosen as a electrode.
Ti electrode is used widely in molecular electronic ,  i have found a reference http://pubs.acs.org/doi/pdfplus/10.1021/nn401357p,(The file is too large, and i can not attach it) it is metal-GNRs-metal connection, how to construct the Ti-GNRs-Ti device in ATK?

i need your help!

thanks very much!

126

General Questions and Answers / Re: how to export the bandstructure date to the Origin readable format in 13.8.1

« on: April 22, 2014, 18:11 »

thank you very much, i will try it.

127

General Questions and Answers / how to export the bandstructure date to the Origin readable format in 13.8.1

« on: April 20, 2014, 18:37 »

i am using the version 13.8.1, and now, the bandstructure is  showed in VNL by bandstructure analyzer,  but i want to show it in Origin, i notice there is a choice to choose " EXPORT Date as Text", but it seems has some needless information for origin.

So i want to know is there a direct way to export data to origin?

thanks!

128

General Questions and Answers / which is spin-up component in transmission spectra

« on: May 21, 2013, 14:25 »

i get the transmision spectra in vnl , but i don't know the red and blue lines represents the spin components?

the red is up? black is down?


and another question is when i export data for the origin software,the end of export files contains the these words:
# Constant line number 0
 -9.996172e-01   0.000000e+00
  1.199541e+00   0.000000e+00
 

what do these mean?

129

Installation and License Questions / license error

« on: May 20, 2013, 09:54 »

i have got a trial license just now, but it seems has some problem:
please help me. thank you.

130

General Questions and Answers / how to export the relaxed geometry in the *.nc into another *.py

« on: May 20, 2013, 06:45 »

i relaxed a two-probe system, and i set the i/o parameter as fault.

device_configuration.setCalculator(calculator)
nlprint(device_configuration)
device_configuration.update()
nlsave('analysis.nc', device_configuration, labels=['relax-parameters'])
 
device_configuration = OptimizeGeometry(
        device_configuration,
        max_forces=0.05*eV/Ang,
        max_stress=0.05*eV/Ang**3,
        max_steps=200,
        max_step_length=0.5*Ang,
        trajectory_filename=None,
        optimizer_method=QuasiNewton(),
        )
nlsave('analysis.nc', device_configuration, labels=['relax'])
nlprint(device_configuration)
 

now, i want to calculate the transmission spectra, there i want to write another *.py. in vnl.
so i need the relaxed geometry, how to export  the geometry in *.nc, and how to import it into the vnl as the input?

and i saw the *.nc file, and find some "Object                            Id
                                                      Device configuration          gID000
                                                      Device configuration           gID001
which one is the final relaxed geometry?

                                           

131

General Questions and Answers / Re: about some parameters in the New Calculator of 12.2.8

« on: May 17, 2013, 04:17 »

you said the For the most accurate calculation always use SCF. SCF means that you perform a self consistent calculation of the electron density, and it is not related to how the relaxation is done.

i have saw the words in the step 4 the example of
http://quantumwise.com/publications/tutorials/mini-tutorials/95-optimizing-the-geometry-of-a-two-probe-system[]http://quantumwise.com/publications/tutorials/mini-tutorials/95-optimizing-the-geometry-of-a-two-probe-system[[/url]
Therefore, double-click the inserted "New Calculator" block in the right-hand panel, and open the "Iteration control parameters". Here, place a tick-mark in the box "No SCF iteration". This will cause ATK to run through only the equivalent bulk calculation, but not perform a full self-consistent calculation with transport boundary conditions, for each step in the geometry optimization[/b]

so here NO SCF interation is related the relaxation,
here what is the meaning of NO SCF interation?
so i don not  understand, relaxed only the central regoion or the whole system? the eletrode can be relaxed in 12.2.8?

132

General Questions and Answers / about some parameters in the New Calculator of 12.2.8

« on: May 14, 2013, 11:14 »

Dear all:
i have some issues unclear about the setting up in the New Calculator, so please help me ;

first if i choose the ATK-DFT option, in the basic settings, there are a box "NO SCF interation", i saw in the example http://quantumwise.com/publications/tutorials/mini-tutorials/95-optimizing-the-geometry-of-a-two-probe-system , it says click it means only relax the scatter region? the eletrode is fixed?
 
but when i do a scf calculation, and then calculate the transmission spectra, the electronic density SCF interaction is needed, why in the another example [url]]http://quantumwise.com/publications/tutorials/mini-tutorials/95-optimizing-the-geometry-of-a-two-probe-system , it says click it means only relax the scatter region? the eletrode is fixed?
 
but when i do a scf calculation, and then calculate the transmission spectra, the electronic density SCF interaction is needed, why in the another example http://http://quantumwise.com/documents/manuals/latest/VNLTutorial/index.html/chap.gnr.html , the part 3. Open the second New Calculator block, and select the Extended Hückel calculator this time.
 the NO SCF interaction is still chosed.

i saw several examples, some classic potential is used in relaxing process. so i am wondering in a serious calculation(for publication), it is OK? because i used DFT method  in 2008 version. and have no idea about the classic potential method.   

where is my wrong, please help me make these questions clearly?

133

General Questions and Answers / Re: how i put a one-by-one calculation in a *.py file

« on: May 14, 2013, 10:22 »

i assume that the geometry configuration is not influenced by the spin, so i put the initial spin setup after the geometry relax.

i have  several related question about the work flowing: 

if i do a relaxing calculation without spin , so in the first New Calculator button,i set the spin  is unpolarized. 
then i do a scf calculation with spin. should i put a New Calculator button once again after Optimization button. so i can reset some parameters related spin ?

134

Installation and License Questions / Re: is there a way to install the ATK12.2.8 in a command line

« on: May 14, 2013, 08:55 »

yes, thank you.

it works fine now .

135

General Questions and Answers / how i put a one-by-one calculation in a *.py file

« on: May 14, 2013, 05:53 »

i want do a complete calculation  for a two-probe system.

first: relax.
second: scf with initial spin
third:    calculate mulliken population and  spin-polarized transmission spectrum

so the working follows: see the attachment.

it is right?