Topics

16

General Questions and Answers / FHI-aims

« on: April 28, 2016, 01:18 »

Dear Sir,
If the ATK license contains FHI-aims features, then can we use in separately installed FHI-aims software?

Thanks
Ramkrishna

17

General Questions and Answers / SO along with LSDA+U

« on: April 23, 2016, 08:46 »

Dear Sir,
Is it possible to consider spin-oribit coupling (SO) along with LSDA+U in ATK 2015.1?

Thanks
Ramkrishna

 

18

General Questions and Answers / data extraction

« on: April 21, 2016, 19:22 »

Dear Sir,
Is it possible to extract the effective band structure data? There is no option in the analyzer tab.

Thanks
Ramkrishna

19

General Questions and Answers / transmission in log scale

« on: April 6, 2016, 23:45 »

Dear Sir,
How to get transmission in log scale? 

Thanks
Ramkrishna

20

General Questions and Answers / unit cell transformation

« on: March 7, 2016, 15:22 »

Dear Sir,
Can you please let me know what is the procedure to transform a unit cell to fractional type (like sqrt(3)xsqrt(3) or sqrt(13)xsqrt(13)) supercell in crystal builder? As for example, how can I transform a regular Silicene unitcell to sqrt(3)xsqrt(3) Silicene unitcell?

Thanks
Ramkrishna

21

General Questions and Answers / Region-dependent "c" parameter for MGGA-TB09

« on: November 3, 2015, 23:24 »

Hi All,
In the new feature option I have seen a "Region-dependent "c" parameter for MGGA-TB09". Can you please let me know how to implement that? Just like region, is possible to specify for a particular atom within the crystal?

Thanks
Ramkrishna

22

General Questions and Answers / phonon DOS

« on: June 11, 2015, 18:32 »

Dear Sir,
Does the ProjectionList argument inactive in case of phonon DOS? I am getting error like "got an unexpected keyword argument 'projection_list' " or invalid syntax when I call this argument in the DOS calculations. However the same is working fine for electronic DOS. Is there any way to get the projected phonon DOS?

Thanks
Ramkrishna

23

General Questions and Answers / Joint density of states

« on: May 22, 2015, 20:11 »

Dear Sir,
In optical spectrum we can directly calculate the real and imaginary part of the dielectric. However, we know the imaginary part is determined by the joint density of states (joint DOS). Is it possible to calculate (or extract from the Im_epsilon) the joint DOS?

Thanks
Ramkrishna

24

General Questions and Answers / coordinate extraction

« on: May 20, 2015, 16:02 »

Dear Sir,
Is it possible to extract the coordinates and lattice parameters of each steps from the optimization trajectory file? Or is it possible to save each coordinate files separately in the time of structure optimization? Actually,  the trajectory file always open the final structure in the builder.

Thanks
Ramkrishna

25

General Questions and Answers / Tellurium MGGA.TB09LDA basis set

« on: March 28, 2015, 19:40 »

I think, the implemented tellurium MGGA.TB09LDA basis set is not a correct one . What I can remember that Te LDA basis set was wrong in 11.2, and may be this MGGA.TB09LDA is still not updated.  Please check that once.

Thanks
Ramkrishna

26

General Questions and Answers / transmission values

« on: September 2, 2014, 22:03 »

Dear Sir,
     I was looking the tutorial " http://quantumwise.com/documents/tutorials/latest/Fe-MgO-Fe/index.html/chap.mgo.anti.html " for the transmission spectrum/k-resolved transmission. However, I found that in the transmission spectrum the value is in the order of 10^-6 but in k-resolved, it is showing the maxima in the order of 10^-4. So, I am quite confused why the values in k-resolved is high with respect to the value from the trans. spectrum? If you will discuss this issue, it will be very much helpful to understand the transmission plot.

Thanks
Ramkrishna

27

General Questions and Answers / Job terminated

« on: July 12, 2014, 14:19 »

Dear Sir,
The job has been terminated with the following error. Whats it mean? How to recover from this problem. Please help.

/gpfs/apps/x86_64-rhel6/quantumwise/atk-13.8.1/atkpython/bin/atkpython: line 7: 29613 Killed $EXEC_DIR/atkpython_exec $*

Thanks
Ramkrishna

28

General Questions and Answers / checkpoint file

« on: July 10, 2014, 20:16 »

Dear Sir,

    I have two points here,

   1)   In case of checkpoint handler if I will fix it in the following way for the I-V curve calculations (in the explicit voltage list code to calculate transmissions), will it be correct? I am really confused here. Suppose the my scf calculation is interrupted after a voltage of 0.25V but before the converged result of 0.5V, will it save upto that point within that checkpoint file?

Code

#----------------------------------------
# Device Calculator
#----------------------------------------    
calculator = DeviceLCAOCalculator(
    basis_set=basis_set,
    exchange_correlation=exchange_correlation,
    numerical_accuracy_parameters=device_numerical_accuracy_parameters,
    electrode_calculators=
        [left_electrode_calculator, right_electrode_calculator],
    )

[color=red]# Set Checkpoint file
checkpoint_handler = CheckpointHandler('/home/ram/Desktop/checkpoint_files/checkpoint.nc', 20*Minute)

calculator = DeviceLCAOCalculator(checkpoint_handler=checkpoint_handler)[/color]

# Define the bias voltages for the I-V curve
voltage_list=[0, 0.25, 0.5, 0.75, 1.0]*Volt

# Loop over the bias voltages
for voltage in voltage_list:
    # Set electrode voltages and use the self-consistent state of the previous calculation as starting guess
    device_configuration.setCalculator(
          calculator(electrode_voltages=(voltage/2, -voltage/2)), 
          initial_state=device_configuration)
    device_configuration.update()
    nlsave('device.nc', device_configuration)
     
    # Calculate and save the transmission spectrum for each bias
    transmission(device_configuration)

2) Now, if I want to restart the scf calculation from that checkpoint file for the next bias (i.e. 0.5V) then can I use the command

Code

device_configuration = nlread("checkpointfile.nc")[0]
device_configuration.update(force_restart=True)

in the place of the device_configuration.update() which is within the bias loop [ http://quantumwise.com/publications/tutorials/mini-tutorials/142-restarting-stopped-calculations ] to start from that interrupted stage?
As this  device_configuration.update() is within the loop, so I am quite confused whether when it goes for next scf calculations for voltage 0.75V, will it consider the 0.5V device configuration as the initial configuration or not (I mean, will it take the checkpoint file again for its initial state or the 0.5V device configuration?).

Or if there is any specific way to use the checkpoint file to use for a interrupted I-V calculations after a certain iteration of a specific bias without restarting from the previous converged state, then please let me know. It will be very much helpful to handle a long simulation.


Thanking you,
Ramkrishna

29

General Questions and Answers / Fermi level

« on: July 3, 2014, 16:01 »

Dear Sir,
     I have a very general query actually. I always face a question from different people that DFT is basically calculating bandstructure at 0K, so the Fermi level should be at the valence band maxima, but in your BS it is not. I have one intuitive idea about that but if you clarify this, then it will be very much helpful to make them understand. 

Thanks
Ramkrishna

30

General Questions and Answers / Total energy

« on: June 21, 2014, 02:58 »

Dear Sir,
     In case of structure optimization, is it possible to extract the total energy of a system from each step of the trajectory file?

Thanks
Ramkrishna