Messages

31

General Questions and Answers / Re: projection

« on: July 21, 2017, 09:24 »

Thank you for your reply.

In the 'projection' key word, I see a choice named 'm-quantum-number'. However, I dont know whether it is the one that I want. It is well known that  in a atom, take d orbitals as an example, the d orbitals that m=-2, -1, 0, 1, 2 do NOT directly corresponds to the commonly used dxy, dyz, dzx... Usually there is a simple transformation between these two sets of orbital. Therefore, My question is, which kind of orbital is the ATK provided?

 

32

General Questions and Answers / projection

« on: July 21, 2017, 08:07 »

Hi,
   In ATK2017, is it possible to obtain the projected DOS more accurately? For example, to my knowledge, the old ATK only provides the d-states as a whole for projected DOS, in the new version the d-states projected DOS can be further divided into dxy, dyz, dzx...?

33

General Questions and Answers / Soft model in pnonon spectra

« on: May 2, 2017, 05:50 »

Dear all,
I have two questions.
First, for phonon spectra, we found some negative frequencies. I want to know whether the negative frequencies in solid can be called as soft model , i.e., negative frequencies and soft models  have the same meanings in solid?
( It is well known that negative frequencies in molecules or clusters are usually used to indicate transtion states)

Second, through the "VibrationalMode", can we obtain the specific vibration of a negative frequency?

Thank you very much for your reply.

34

General Questions and Answers / 2016.r1 can not export data for IETS

« on: July 12, 2016, 02:34 »

I test an example, but found that there is no choice for the IETS to export data as TXT file (see the figure in the attachment).
I want to know how to export data as TXT file for futher treatment (such as Origin ).
Thank you

35

General Questions and Answers / ep coupling

« on: June 23, 2016, 16:25 »

Hi,
We know that in present version of ATK, one can include the electron-phonon coupling in the transport properties (such as IV curve). I have two questions:
1. In ep coupling transport calculations, the electronic and phononic properties can be done at different theoretical levels?  For example, DFT for the former and classical potential for the latter.
2. Is it possible to include spin polarization in the  ep coupling transport calculations? i.e. one can obtain the UP and DOWN spin current after the ep coupling is included?
Thank you for your reply.

36

General Questions and Answers / Is it possible for ATK to model the transport properites of a real 2D material ?

« on: March 15, 2016, 01:26 »

Hi everyone,
   Is it possible for ATK to model the transport properites of a real 2D material  along different directions?
   For example, for 2D graphene (not 1D nanoribbons), is it possible for ATK to calculate the transport properties along zigzag and armchair directions?
Thank you.

37

General Questions and Answers / Is it possible for ATK to calculate phonon local density of state?

« on: March 2, 2016, 15:59 »

Hi
In the attament files, the first figure is phonon local density of state (PLDOS), the sencond is the corresponding formula.  Could the ATK calculate the PLDOS, or provide some scripts to calculate it?
Thank you very much.

38

General Questions and Answers / Re: How to deal with excessive memory usage

« on: January 20, 2016, 02:04 »

Thank you for your reply, Blom,
     During the calculation, according to your guide, I used 32 cores with 16 MPI. However, the problem still existed. In addition, the total memeory advised by ATK calculater is about 2000 MB (=2 GB).
    Could you give me some further suggestions?

39

General Questions and Answers / How to deal with excessive memory usage

« on: January 19, 2016, 03:18 »

Dear,
Recently, I try to test a IV curve of a device configuration. The calculation is always abnormally terminated because of  "excessive memory usage". I decrease the basis sets (from DZP to SZP) and K point (from 100 to 20) but the problem still exists. The attachment is the input file.

| Real space grid sampling is (219, 271, 427) in a, b, and c directions.       |
|                                                                              |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
|                                                                              |
| Storage of atomic core grids requires   193 MB per grid                      |
|                                                                              |
+--------------------------------------------------------------------------


The above information is obtained from the log file. My comprehension is that the total memory needed is 219X271X427X193 MB=4776377 GB, a very large number and can not achieve in any super computor . I wonder why such a simple system (only contains C and H atoms) needs so many memory?

Thank you in advance.

40

General Questions and Answers / Re: How to find the spin-up and spin-down electrons?

« on: November 14, 2015, 01:33 »

I see now that something may be wrong.
thanks for reporting the issue. We will fix it and come back to you soon.

Thank you for your reply, Martinez.
I have another question. Sometimes  the unpaired electrons in a magnetic devices are NOT an integer, or the influence  of some calculated parameter (such as the so-called 'temperature' of electrode) is significant . In these cases, how to plot the eigenstate of the device at fermi level or a peak in the bias window? Because it is difficult to fix the quantum number of the eigenstate. Is there another way to do this if the Transimission Analyzer has some problem.

41

General Questions and Answers / Re: How to find the spin-up and spin-down electrons?

« on: November 5, 2015, 08:34 »

BTW, there may be a bug in 2015. I found that, in "Transmission Analyzer", only the plot of spin-up eigenstates can be given, where the spin-down eigenstate can NOT be directly shown.(At the same time, in the viewer, open the  corresponding  "properties"window, there is No choice about isosurfaces  for spin-down states. But the  isosurfaces  choice for spin-up state exists. )

everything works fine in 2015.0. You can plot the spin up and spin down transmission spectra.
Please attach your input/output files to check what is going on.

Thank you for your reply.
Althogh the transmission spetra are OK, please note that it seems that the 'spin-down eigenstate' in the Transmission Analyzer may have some problems,i.e., for a spin-polarized system, the spin-down eigenstate can not be well displayed through the 'eigenstate' option in Transmission Analyzer.

42

General Questions and Answers / How to find the spin-up and spin-down electrons?

« on: November 3, 2015, 14:45 »

Hi,
   It is well known that, for magnetic systems (magnetic molecule or solid), the numbers of spin-up and spin-down eletrons are different. However, I found it is difficult to directly obtain the numbers of spin-up and spin-down electrons after a spin-polarized calculation in ATK. If I do not intend to perform a mulliken analysis, can I directly obtain the number of unpaired electrons after a spin-polarized calculation (i.e. the respective number of spin-up and spind-down electrons, and this should be the basic information for the output file)? Because in some cases, for example, I need to know the quantum number of the highest occupied states of the magnetic systems, where the spin-up and spin-down states are not degenerate.

In addition, even though a mulliken analysis is performed, can I directly obtain the number of unpaired electrons ? Because for a complicated system, to count the unpaired electrons on every atoms and then add all of them one by one is very unconvenient.
 
BTW, there may be a bug in 2015. I found that, in "Transmission Analyzer", only the plot of spin-up eigenstates can be given, where the spin-down eigenstate can NOT be directly shown.(At the same time, in the viewer, open the  corresponding  "properties"window, there is No choice about isosurfaces  for spin-down states. But the  isosurfaces  choice for spin-up state exists. )

Thank you!

43

General Questions and Answers / a question about new job manager in 2015

« on: November 3, 2015, 00:54 »

Hi,
Recently, we found that the new job manager in 2015 is differenet from those in old versions. Since it now adopts client-server strcuture, we want to know that if it is possible to install the license ONLY in the client, and submit a calculation to a remote server through the client (if we have many servers, this is important. For example, if one of the servers is stopping, we can choose another one instead and do not need to consider the location of the license)?
Thank you for your reply.

44

General Questions and Answers / The meaning of the current in Z direction

« on: October 20, 2015, 14:00 »

Hi,
   In the IV-Plot (see the 1.jpg in the attachment), one choice of the spin is "Z". Its meaning is unclear for me , and I have two questions. 
   1. What is the physical meaning of the choice Z? Is it about non-collinear (or non-collinear with spin orbit coupling) calculation?
   2. In common spin-polarized (collinear) calculation, the 'Z' result is different from that of the 'sum, up or down'. I wonder why the difference occurs.
Thank you.

45

General Questions and Answers / a possible bug in 2014.3?

« on: September 30, 2015, 16:36 »

Hi,
   Recently, I test a spin polarized calculation (see the 1.py ). However, when i tried to plot the spin density i failed.
The problem is that there are no proper choices such as spinup+spindown, spinup-spindow etc. appear in the pannel (see 1.png), which is different from the following tutorials (http://quantumwise.com/documents/tutorials/latest/GrapheneBloch/index.html/electrondensity.spin.html),
   I want to know why. Is it a bug in 2014.3?
 Thank you in advance.