Messages

1

General Questions and Answers / Re: Interface between Graphene & Mos2

« on: April 17, 2022, 20:23 »

If you don't have experimental data to begin with, I'd would use 2.5 Angstroms as a guess for the smallest interatomic distance. Then, the optimun distance will be determined by the OptimizeDeviceConfiguration study object using LCAOCalculator or SemiEmpiricalCalculator (in case there is appropiate parameters for your system).

2

General Questions and Answers / k-points Fermi level, band structure and transmission spectrum

« on: April 14, 2022, 20:32 »

Dear QuantumATK users,

1) How is the Fermi level computed in QuantumATK?  How it depends on the k-points number? The variation of the Fermi level with respect to the k-points number indicates a change in the number of energy levels of the band structure? or it is possible the band structure converges with respect to the k-points number but the Fermi level still varies?

2) The Fermi level and the transmission spectrum (calculated from bulk) should converge, with respect to the k-points number, at the same k-points number?

3

General Questions and Answers / Transmission Spectrum from a Bulk Configuration - Reference

« on: April 8, 2022, 00:12 »

Could you please refer me to a reference detailing the theory implemented in QuantumATK to calculate the trasmission spectrum from a bulk configuration?

4

General Questions and Answers / Re: Device with Hexagonal system

« on: April 6, 2022, 23:28 »

You should be able to build a device from a cell if C is _|_ to the AB plane, so that is not a problem for an hexagonal cell. If Device from Bulk is not working, I think in two scenarios: 1) the cell is not long enough in the C axis, which you can solve using Bulk Tools -> Repeat.  2) C is not along the z axis, which you can solve using Builders -> Surface (cleave).

5

General Questions and Answers / Symmetrize or not to symmetrize?

« on: April 2, 2022, 21:32 »

Dear QuantumATK users,

When should I (or not) use Bulk Tools -> Crystal Symmetry Info -> Symmetrize?
What calculations could this operation affect?

6

General Questions and Answers / Building a device from a triclinic unit cell

« on: March 21, 2022, 03:54 »

Dear QuatumATK users,

I want to build a device for a pure organic material to calculate the transmission spectrum under bias for different transport directions. However, the crystal structure is represented by a triclinic unit cell. I've tried two ways to make the C vector orthogonal to the AB plane, but I haven't had success.

1) When using the supercell option in bulk tools, none of the orthorhombic, tetragonal or cubic crystal systems make the alpha and beta angles exactly 90°.

2) When trying to use the surface (cleave) option in the builder tool, none of the orientations I've tested let me choose the out-of-plane cell vector as periodic and normal (electrode).

Is there something related with the symmetry of the crystal that makes this task not possible?
In case it is possible, How can I do it?

Thank you in advance for your help.

I attached the CIF file.