Messages

1

News and Announcements / Bugfix update VNL-ATK 2017.1

« on: September 9, 2017, 00:11 »

A bugfix update to VNL-ATK 2017 has been released (version 2017.1).

Download it from http://quantumwise.com/products/download.

This update contains a substantial amount of bug fixes, in particular several that fix various crashes. We are not aware of any bugs (solved or not) that would cause decidedly wrong results or errors in calculations (except very minor ones), but there were quite a few scenarios in which ATK 2017.0 would crash. The new 2D plot framework also received a touch-up in this release, and we spent some time solving minor annoying issues in VNL to improve the user experience.

For the full list of updates please check the official 2017.1 bugfix release letter.

2

News and Announcements / Bugfix update VNL-ATK 2016.1

« on: September 9, 2016, 13:31 »

A bugfix update to VNL-ATK 2016 has been released (version 2016.1).

Download it from http://quantumwise.com/products/download as usual.

NOTE: In a sense you don't really need to upgrade unless you have experienced any of the specific problems listed below, which are fairly rare and you will definitely know if you were affected. On the other hand it's always a good idea to run the latest version :-)

Major issues

• OMX basis sets were not scripted properly in Python scripts and NC files. This is fixed + support has been added for opening broken NC files produced by 2016.0 (in case you manually fixed the script problem)
• ATKClassical performed multiple license checkouts when running long MD calculations

For more details and a complete list of fixed issues, see the release letter.

3

General Questions and Answers / Re: Discrepency in Effective mass calculation

« on: May 29, 2015, 08:04 »

One should be a bit careful with Vurgatfman's paper. If you read carefully the notes (always do that!) about the L masses in InAs, you will find that they are neither experimental nor computed, but "guesstimated" from the DOS effective mass.

That said, 1.8 is very high, so indeed the curvature is not very accurate with the basis set you use (did you try other ones?).

4

News and Announcements / Survey from QuantumWise

« on: February 3, 2015, 00:14 »

A survey was sent out over the weekend to a large number of ATK and Virtual NanoLab users, mainly to persons who requested a trial license.

We hereby confirm that the email is not spam, and it is correct that you can obtain an extended trial license by completing the survey.

The survey was formulated by a small group of master students from Judge Business School in Cambridge, UK, who work as consultants for QuantumWise. Unfortunately, they didn't double-check the content of the email and survey before sending it out, resulting in a misspelling of Virtual NanoLab throughout the email and survey, and other minor mistakes.

Despite these unfortunate mistakes we appreciate all completed forms, which we can use to improve the quality and user experience of our products. If you have additional questions about the survey, please contact info@quantumwise.com.

5

News and Announcements / Forum updated

« on: January 23, 2015, 11:15 »

The Forum has been updated to a newer version! Hopefully it will feel and work better than before, but during the first few days or even weeks, there may be a few hickups. Don't hesitate to report them by posting to this thread!

For now we know that the country flags and syntax highlighting of code don't work.

6

General Questions and Answers / Re: Transmission Spectrum Analysis

« on: October 9, 2014, 09:43 »

This should be fixed in 2014.1 which is now available for download.

7

General Questions and Answers / Re: electron transfer rate from electrode to the molecule

« on: October 23, 2013, 21:16 »

No such script exists at this moment, but we'll consider it for the future. Thanks for your interest and feedback - we appreciate suggestions for new features, they are just not always possible to deliver very quickly.

8

News and Announcements / ATK 13.8 released

« on: October 23, 2013, 21:14 »

Enjoy all the new features like phonon calculations, MD, noncollinear spin, enhanced analysis functionality, projects to organize data, better 3D performance, ABINIT integration, van der Waals, etc. See the release letter for more information!

9

General Questions and Answers / Re: How to ripple a graphene ?

« on: May 14, 2013, 10:41 »

There are no secrets in the plugin, the formula is given in the code:

Code: python

def buckle(x, width, length, amplitude, z_start, z_end, periods_y, periods_z):
    """
    Function for converting a nanosheet coordinate into a wobbled graphene nano-sheet
    @param x         : Coordinates of an atom
    @param width     : wave length of the buckling in the y-direction
    @param length    : wave length of the buckling in the z-direction
    @param amplitude : Buckling in units of Angstrom
    @param z_start   : z value for starting the buckling
    @param z_end     : z value for ending the buckling
    @param periods_y : number of periods in y
    @param periods_z : number of periods in z
    """
    # do not buckle for z > z_end
    z = x[2]
    z = min(z,z_end)
    # do not buckle for z < z_start
    z = z - z_start
    z = max (z,0.0)
    # find the buckling phase of the current atom in the y and z directions
    if periods_y==0:
        phase_y = math.pi/2
    else:
        phase_y = 2.*math.pi*(x[1]-width/2.)/width * periods_y
    if periods_z==0:
        phase_z = math.pi/2
    else:
        phase_z = 2.*math.pi*(z-length/2.)/length * periods_z

    # return atom position of the wrapped atom
    return x + numpy.array([amplitude*math.sin(phase_y)*math.sin(phase_z),0.0,0.0])

That is, a function f(y,z) is added to the x coordinate of each atoms, and essentially f(y,z)=A*sin(y)*sin(z), but with the small adjustment that
a) it's possible to specify an excluded zone on the edges in Z, where f=A*sin(Y); this is so we can easily ripple transport systems;
b) the Y and Z coordinates must of course be renormalized so we can use the sin() function normally; these are the "phase" coordinates.

10

News and Announcements / ATK 12.2.2 released - support for charged electrodes

« on: July 3, 2012, 23:14 »

ATK 12.2.2 is released to give users access to one new feature (charged electrodes), a performance and quality update to another one (complex band structure), and a few small bug fixes.

See the release letter for all details.

11

General Questions and Answers / Re: Installation on ubuntu was done! but cannot reopen ATK12.2.1 32bit

« on: June 25, 2012, 10:15 »

There may be a confusion of the paths. It would be a good idea to clean out references to 12.2.0 or earlier releases from your .bash_profile file.

Also check if you can start VNL by typing "vnl" in a terminal window.

12

News and Announcements / Bug fix release ATK 12.2.1

« on: June 11, 2012, 13:17 »

We have today released ATK 12.2.1, which contains a few critical bug fixes, several minor ones, and also a few new features like support for FHI-aims and CASTEP import/export.

See the complete release letter for all details.

13

General Questions and Answers / Re: Problem: Fatal error in MPI_Allreduce

« on: November 28, 2011, 12:39 »

I haven't had more than 10 secs to look at this, but when I look at the kind of graph you showed, I would think your labels are displaced by 1: the high-memory area is probably the equivalent bulk and the part you marked transmission is more likely the two-probe. You can double-check this by looking at the time used for each segment - this info is in the log file, each step shows when it started and finished (grep for "2011").

14

News and Announcements / ATK 11.8.1 released

« on: November 21, 2011, 16:38 »

Today we released ATK 11.8.1, a minor update. It is not really necessary to upgrade from 11.8.0 unless you are specifically affected by the handful of small bugs that were solved in this version.

Of course, if you haven't yet downloaded and installed ATK 11.8.0, this is the version you should go for.

ATK 11.8, released earlier this month contains a lot of new exciting features like

• Calculate dielectric constant and other optical properties via Kubo-Greenwood formalism
• Meta-GGA - gets the band gap right in DFT for many semiconductors and insulators
• ATK-SemiEmpirical has been radically extended, with DFTB, spin and forces in Huckel, and user-defined Slater-Koster models.
• Nudged elastic bands (NEB) to compute transition states and reaction barriers
• Over 200 new HGH pseudopotentials added, incl. many semi-core potentials (and support for Lanthanum)
• Small updates in VNL, incl. a new Job Manager that can kill and rerun jobs and a Custom Scripter which adds GUI support for external codes, like VASP - or your own home-grown code
• Multigrid solver updated for DFT, used too much memory before (when using gates)
• Reintroduced "old gate" method (rigid shift), but smarter
• Improved CIF import
• Support for LDA+U in the Scripter
• License configuration tool
• Minor bug fixes, mostly in VNL

See the release letter for the full list of updates, and the list of features for a complete list of features in ATK.

If your license file contains a feature version 11.8 or above, you can just download and install 11.8 today! There is no real risk involved - all old scripts are compatible and give the same results as before.

We are always very interested in receiving feedback and comments about the new version and in general about ATK/VNL, for instance through the dedicated Forum section for discussions about future releases.

15

General Questions and Answers / Re: Trouble with Segmentation fault

« on: June 22, 2011, 04:54 »

First of all it does appear the default temperature is not stated correctly in the manual. Indeed it's 300 K. Sorry for the inconvenience, although for all practical purposes the difference is probably completely negligible, since the temperature only serves to smear the Fermi level a bit.

It does seem we have some problem with metallic and dielectric regions in DFT, and we are now implementing a new multigrid solver for 11.8 which should improve on this situation.

I'm not 100% sure it's a matter of running out of RAM, although it would be helpful for us if you could estimate how much RAM is needed with and without the regions for one of the jobs that did run through.