Recent Posts

1

General Questions and Answers / Re: Crystal Structure InGaZnO4

« Last post by Anders Blom on Today at 22:47 »

Actually, nobody has done a forcefield for IGZO before as far as I know, so that would be extremely valuable in general. We could provide support and guidance for that effort, it could actually be a great test-case for some new features we will introduce in December. You can reach out to me separately on email to discuss this further.

2

General Questions and Answers / Re: Crystal Structure InGaZnO4

« Last post by Anders Blom on Today at 22:41 »

MD is more systematic, and you have more control, esp. since it starts from the actual crystal you have. The prebuilder is more brute-force, kind of just throwing the right ratio of atoms in a pot and stir it. The output still has to be equilibriated of course, but it does save time by skipping the melt part, and it does generate a very random structure initially, whereas melting the crystal might retain some of the long-range order. You do need a decent idea of the density to begin with for the prebuilder though. I think it's worth trying the prebuilder in your case, but you still need to do MD on it.

Btw, if this is a system you want to study in great detail, it could be really worthwhile to fit an MTP forcefield for it. That way you can do all kinds of thermal and mechanical studies with MD in hours rather than weeks, in the end! The fun part is that you can basically automatically generate the MTP while amorphizing it with DFT, which you have to do anyway.

3

General Questions and Answers / Re: calculating optical properties (permittivity) at very low frequencies (THz)

« Last post by Anders Blom on Today at 21:31 »

Google is kind of nice for these types of questions.

4

General Questions and Answers / Re: calculating optical properties (permittivity) at very low frequencies (THz)

« Last post by Darlan on Today at 17:59 »

Hello,
I'M TRYING TO FIND THE PERMITTIVITY OF PHAGRAPHENE AS A FUNCTION FREQUENCY (TERAHERTZ) INSTEAD OF eV. COULD YOU GIVE ME SOME ADVICE, PLEASE? THANKS FOR YOUR HELP.

5

General Questions and Answers / Re: Graphene Mobility

« Last post by gozde on Yesterday at 15:00 »

Thank you for your comments.

Error message related to the "electron_bands=Automatic"  is at the attachment. "No electron_bands found. Try to increase the energy_range." is written in the log file. The energy range is from -0.5 to 0.5 in the tutorial.

6

General Questions and Answers / Question of inital state in IVCharacteristics object

« Last post by rebacoo on Yesterday at 14:57 »

Dear QuantumATK staff:
      i want to calculate the IV of MoS2 FET device using IVCharacteristics object. however, the FET is hard to converge at certain gate voltage. So, i want to  use the initial state object to provide a better starting guess. For example, the FET is converged in 0.1V gate voltage, i want to use the initial state of 0.1V gate to calculate 0.5V gate voltage. However, the script doesn't seem to work.
Here is the script (the corresponding parameters are omiteed. PS:  ATK version is QuantumATK2022 ), :
**************************
# -*- coding: utf-8 -*-
# -------------------------------------------------------------
# Two-probe Configuration
# -------------------------------------------------------------
# -------------------------------------------------------------
# Left Electrode
# -------------------------------------------------------------
...
# -------------------------------------------------------------
# Right Electrode
# -------------------------------------------------------------
....
# -------------------------------------------------------------
# Central Region
# -------------------------------------------------------------
....
# -------------------------------------------------------------
# Calculator
# -------------------------------------------------------------
#----------------------------------------
# Basis Set
#----------------------------------------
.....
#----------------------------------------
# Numerical Accuracy Settings
#----------------------------------------
....
#----------------------------------------
# Poisson Solver Settings
#----------------------------------------
......
#----------------------------------------
# Contour Integral Settings
#----------------------------------------
.....
#----------------------------------------
# Electrode Calculators
#----------------------------------------
......
#----------------------------------------
# Device Calculator
#----------------------------------------
......
# -------------------------------------------------------------
# Initial State
# -------------------------------------------------------------
old_calculation = nlread('Device_MoS2-gate0.1.hdf5', DeviceConfiguration)[0]

device_configuration.setCalculator(
    calculator,
    initial_state=old_calculation,
   )

# -------------------------------------------------------------
# IV Characteristics
# -------------------------------------------------------------

# Gate-source voltages
gate_source_voltages = numpy.linspace(0.5, 0.5, 1)*Volt

# Drain-source voltages
drain_source_voltages = numpy.linspace(0.65, 0.65, 1)*Volt

# File name
filename = 'Device_MoS2-gate.hdf5'

iv_characteristics = IVCharacteristics(
    configuration=device_configuration,
    filename=filename,
    object_id='Device_MoS2-gate_IV_',
    gate_regions=[0, 1],
    gate_source_voltages=gate_source_voltages,
    drain_source_voltages=drain_source_voltages,
    energies=numpy.linspace(-2, 2, 401)*eV,
    kpoints=kpoint_grid,
    self_energy_calculator=RecursionSelfEnergy(),
    energy_zero_parameter=AverageFermiLevel,
    infinitesimal=1e-06*eV,
    log_filename_prefix='Device_MoS2-gate_IV_',
    number_of_processes_per_task=None,
    enforce_zero_transmission_in_band_gap=False,
    source_electrode=Left
)
iv_characteristics.update()
**********************************************************
Is there something wrong with this script? how to modify?  is there any other plan?  Thank you

7

General Questions and Answers / Re: Crystal Structure InGaZnO4

« Last post by chitrapandy on Yesterday at 09:04 »

Thank you for your time and the file.
Meantime I got the  InGaZnO4 Crystal structure from materialsproject which is working without any errors.
I would like to generate a amorphous structure. will the amorphous pre-builder is good choice or MD simualtion?
Can you give your suggestion?
Thank you

8

Installation and License Questions / Re: Executable error when loading Preferences.py file

« Last post by filipr on October 4, 2022, 09:49 »

Did you enable software rendering when installing QuantumATK? Can you show us the content of the file ~/.vnl/software-rendering (Linux) or C:\Users\<USER>\.vnl\software-rendering (Windows)?

The file Preferences.py is part of the QuantumATK source code which is not part of the installed program and thus not accessible to users. The problem is not due to a problem in that file, but because it tries to read a number from a settings file which is likely corrupted.

9

General Questions and Answers / Re: ATK installation

« Last post by filipr on October 4, 2022, 09:22 »

I'm not certain, but it appears that the pymatgen library tries to look for pymatgen or VASP specific settings in your environment.  Be sure that you do not have the following environment variables set/defined before running atkpython:

• Any variable starting with PMG_
• VASP_PSP_DIR, MAPI_KEY and DEFAULT_FUNCTIONAL

If these are set in e.g. your ~/.bashrc file you must either remove the definitions from the that file or manually unset them before running atkpython.

10

General Questions and Answers / Re: BSSE & Possible ATK Bug

« Last post by AsifShah on October 3, 2022, 20:42 »

Thanks Anders Blom.
This was helpful.