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Messages - Umberto Martinez

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31
General Questions and Answers / Re: Multi-core support serial license
« on: July 25, 2016, 10:29 »
Yes, with your license you can do threading over all the cores of your machine http://docs.quantumwise.com/tutorials/job_manager_local.html#threading
This is particularly relevant for classical calculations (ATKClassical).

To run efficient parallel ATK-DFT jobs you need a parallel version of your license to be able to run over several  MPI processes.
You can contact us privately if you would like more info on how to upgrade your license.

32
Links to Resources and Publications / Re: QuantumATK hands on
« on: July 25, 2016, 10:23 »
We are not planning to do that for the workshop in August. We will definitely consider the option for the next events we organize.

33
News and Announcements / VNL and ATK 2016 released
« on: July 21, 2016, 21:18 »
The new VNL and ATK 2016 is now released!

This version features, among many other things, better parallel performance, improved DFT accuracy, a new MD framework, as well as a very exciting new NEGF algorithm for surface calculation - and it's available also for Mac OS X.

See the full release letter.

Download the new VNL-ATK 2016.0 packages

Highlights
  • New basis sets and pseudopotentials (SG15) which improve the accuracy of ATK-DFT substantially (GGA only)
  • Faster electron-phonon coupling calculations - up to 10x improvement in the general code, plus a new approximate spectral method that is even faster
  • Support for noncollinear spin and spin-orbit in the electron-phonon coupling module
  • More quantities can be obtained from a mobility calculation: Seebeck coefficient, thermal conductivity, and the Hall-coefficient and Hall-conductivity tensors
  • Multi-core parallelization per k-point turned on by default - scale bulk calculations to 100s of cores without using any extra options in the input file
  • Enhancements to the Script Generator, making it a lot easier to use also for more advanced features
  • Improved MD/NEB/AKMC framework - multilevel parallel, and entirely new, highly flexible back-engine code
  • State-of-the-art Martyna–Tobias–Klein barostat for MD
  • Lots of new plotting methods in VNL
  • SurfaceConfiguration, a.k.a. one-probe: a new unique approach to simulating real surfaces without resorting to the slab approximation, using NEGF with physically correct boundary conditions
  • PEXSI solver, for large-scale DFT calculations (10,000+ atoms)
  • New k-point grids: Γ-centered odd meshes, and regular grids to span the Brillouin zone edge-to-edge (or cut out a small region) for transmission spectra
  • New Hubbard-U method, with shifts applied to the pseudopotential projectors for each angular momentum channel (similar approach as used in plane-wave codes)
  • Ozaki equilibrium contour; highly stable calculation of the equilibrium density matrix in device calculations. Particularly useful if the electronic eigenvalue spectrum is very deep
  • Verbosity framework, to control the level of output from an ATK calculation in detail
  • Mac OS X version

34
General Questions and Answers / Re: Passivation of Silicon nanowires
« on: June 24, 2016, 23:12 »
can you please save and attach here your configuration?

35
News and Announcements / ATK and VNL hands-on workshop
« on: June 10, 2016, 11:56 »
QuantumWise would like to invite all ATK and VNL users to a hands-on workshop on atomic scale modeling of nanomaterials.
The workshop will take place at QuantumWise’s headquarters in Copenhagen on August 19, 2016. The day will end with a guided visit to Niels Bohr's office.

Read more and sign up today at this link!
Deadline for signing up is July 15th at 16.00 CET.


36
General Questions and Answers / Re: macroscopic average for ElectrostaticDifferencePotential
« on: May 13, 2016, 11:48 »
check edp.py scipt + instructions here: http://docs.quantumwise.com/casestudies/ag_si_interface.html#silicon-doping-and-depletion-layer-length

37
General Questions and Answers / Re: Aluminium bonds
« on: May 10, 2016, 12:48 »
You can try this http://quantumwise.com/forum/index.php?topic=3463

38
General Questions and Answers / Re: Wrong bandgap calculated for Cu2O using DFT+U
« on: May 6, 2016, 20:28 »
2.17 eV is the exp. band gap.
0.62 eV is the calculated one which reproduce previous VASP calculations as reported in table 1 of your reference, 0.67 eV.

You can try MGGA as implemented in ATK to get a better description of the band gap if you need it.

39
General Questions and Answers / Re: FHI-aims
« on: April 29, 2016, 13:58 »
The FHI-Aims  feature in the ATK license is an extra feature that needs to be purchased separately.
Please contact sales@quantumwise.com for more information.

40
General Questions and Answers / Re: part of MPSH orbital outside the unit cell
« on: April 29, 2016, 13:32 »
Drag and drop the configuration on top of the isosurface window. You have the repetition option for the configuration as well.

41
General Questions and Answers / Re: part of MPSH orbital outside the unit cell
« on: April 29, 2016, 13:25 »
In the Viewer you can repeat the isosurface in the three directions (under properties).
This should solve your issue

42
General Questions and Answers / Re: Chemical potential for the surface energy calculations
« on: April 25, 2016, 11:10 »
Regarding Schottky-barrier calculations you may want to check out our latest work where, among other things, we compare the slab approach with the device configuration and NEGF approach as implemented in ATK.
http://arxiv.org/abs/1601.04651
Phys. Rev. B 93, 155302 (2016) http://dx.doi.org/10.1103/PhysRevB.93.155302

43
General Questions and Answers / Re: Creating alloys
« on: April 24, 2016, 20:45 »
The plugins for generating random alloys are available only from VNL 2015.
You should upgrade to this version. Note that if you are only interested in gnerating the structures you can get a free academic VLN version herehttp://quantumwise.com/free-trial/free-vnl

44
General Questions and Answers / Re: Qestion about the two probe system optimization
« on: April 21, 2016, 08:59 »
Quote
Also, I find the ATK-Classical gives a wrong geometry results. For a molecule that is optimzed by ATK-DFT, the ATK-Classical gives a dissociation molecule structure. So, use the ATK-Classical with care.

Absolutely! particular care has to be taken when choosing the classical potential. Check the reference paper carefully to see if your system is compatible with the ones used to test and generate the potential.

45
General Questions and Answers / Re: Qestion about the two probe system optimization
« on: April 21, 2016, 08:57 »
Quote
You mentioned that one does not need the dipole correction in the middle of the vacuum region which can  be applied in VASP for a molecule adsorbed metal surface in the thread http://quantumwise.com/forum/index.php?topic=2666.0.

In ATK, if one use a vacum large enough, then the dipole correction can be ignored? If we use ghost atoms at the metal surface, do the ghost atoms be chosen to move or fix during the geometry optimization? As far as know, the use of ghost atoms will be problmatic in the geomtry optization.

the dipole correction which you can add in VASP is not implemented in ATK. Instead, in ATK it is possible to specify different boundary conditions for the two directions normal to the surface.
This is very well explained in out two related tutorials:
http://docs.quantumwise.com/tutorials/work_function_ag_100.html
http://docs.quantumwise.com/tutorials/work_function_tuning.html

I suggest to constrain the ghost atoms during a geometry optimization.



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