Topics

1

General Questions and Answers / Question:Relationship between DOS and transmission spectrum

« on: May 12, 2010, 10:19 »

the version of our atk is 2.0. And I want to know if the current is the integral of transmission coefficient or the integral of product of transmission coefficient and density of states. Or when calculate transmission coefficient, atk 2.0 has already considered the density of states.

2

General Questions and Answers / How to establish an electrode with two lattic constants in atk 2.0

« on: March 15, 2010, 09:36 »

I have established an electrode of graphene in vnl-2008. For some reasons, I want to calculate the current in atk 2.0. So I need to change the electrode to atk 2.0. But there are two lattice constants of graphene, I don't know how to input. And also when I run it, it says that the unit is wrong. Below is my electrode input. Please help me to correct it.

Code

System::Type Electrode
Method::Type NumOrb
NumOrb::MeshCutoff 100 Ry
NumOrb::BasisSet::Size DZ
Electrode::NumKPoints::C 200
UnitCell::LatticeConstant a=2.4612 Angstrom c=7 Angstrom
%block Electrode::UnitCell
41.75099478      0            0
 0              41.75099478   0
 0               0            8.52516
%endblock Electrode::UnitCell

AtomList::Format Angstrom
%block Electrode::AtomList
 C           15.95349407  15.          1.42086005
 C           15.95349407  15.          2.8417201 
 C           17.18399429  15.          3.55215001
 C           17.18399429  15.          0.71043003
 C           18.41449547  15.          1.42086005
 C           18.41449547  15.          2.8417201 
 C           19.64499664  15.          3.55215001
 C           19.64499664  15.          0.71043003
 C           20.87549782  15.          1.42086005
 C           20.87549782  15.          2.8417201 
 C           22.10599899  15.          3.55215001
 C           22.10599899  15.          0.71043003
 C           23.33649826  15.          1.42086005
 C           23.33649826  15.          2.8417201 
 C           24.56699944  15.          3.55215001
 C           24.56699944  15.          0.71043003
 C           25.79750061  15.          1.42086005
 C           25.79750061  15.          2.8417201 
 C           15.          15.          0.87036002
 C           15.          15.          3.39222002
 C           26.75099564  15.          0.87036002
 C           26.75099564  15.          3.39222002
 C           15.95349407  15.          5.68344021
 C           15.95349407  15.          7.10430002
 C           17.18399429  15.          7.81473017
 C           17.18399429  15.          4.97301006
 C           18.41449547  15.          5.68344021
 C           18.41449547  15.          7.10430002
 C           19.64499664  15.          7.81473017
 C           19.64499664  15.          4.97301006
 C           20.87549782  15.          5.68344021
 C           20.87549782  15.          7.10430002
 C           22.10599899  15.          7.81473017
 C           22.10599899  15.          4.97301006
 C           23.33649826  15.          5.68344021
 C           23.33649826  15.          7.10430002
 C           24.56699944  15.          7.81473017
 C           24.56699944  15.          4.97301006
 C           25.79750061  15.          5.68344021
 C           25.79750061  15.          7.10430002
 C           15.          15.          5.13293982
 C           15.          15.          7.65479994
 C           26.75099564  15.          5.13293982
 C           26.75099564  15.          7.65479994
%endblock Electrode::AtomList

3

General Questions and Answers / About the voltage sweep script(ivcurves.py)

« on: March 11, 2010, 10:58 »

I used the script from http://quantumwise.com/forum/index.php?topic=19.0 to calculate current under a series of voltages. As it said, I put the file ivcurve.py to C:\Program Files\QuantumWise\Virtual NanoLab 2008.10.0\atk\lib\site-packages. But when I calculate current by vnl-2008.10, it said:
Traceback (most recent call last):
  File "c:/docume~1/admini~1/locals~1/temp/tmplq3kcg.nl", line 439, in ?
    ivcurve.runIVcurve (
NameError: name 'ivcurve' is not defined
Terminated Abnormally

Could you help me?

4

General Questions and Answers / The program doesn't give vnl and nc files when do optimization

« on: March 1, 2010, 09:39 »

My version is vnl-2008.10, and I use it to do optimization. I have already give the path of vnl and nc file in nanolanguage scripter, but when the program start, it just gives the out file. This calculation doesn't finish now.
And another question is what the optimization method in atk 2.0 since there are two methods in vnl-2008.10 which are steepest descent and quasi newton.