Messages

1

General Questions and Answers / Band Structure Calculation of Germanium with GGA+U /LDA+U

« on: January 24, 2017, 12:17 »

Hi,

I am trying to calculate band structure of Germanium with GGA+U with Hubbard parameter U for P and D orbitals (Up=-3.7 & Ud=-0.5) as given in the paper

"The effects of uniaxial and biaxial strain on the electronic structure of germanium"  http://www.sciencedirect.com/science/article/pii/S0927025615006709

I am using HGH pseudopotential with GGA.PBE Tier 4 basis set  as suggested by Umberto in this post  http://quantumwise.com/forum/index.php?topic=3202.0.

But the simulation doesn't converge after 100 steps to the required Tolerance.  Do I need to increase the Density Mesh Cutoff to some higher value  from current value of 75 Hatree.  Will that help.

Also I am using ATK 2015.1 so I don't have SG15 pseudopotential which was introduced  in ATK 2016.  So I am not able to use PseudoPotential Projector Shift (PPS) method as suggested by  Jess here

http://quantumwise.com/forum/index.php?topic=4275.0


Any suggestions will be greatly appreciated. I am attaching the script .

Thanks.

2

General Questions and Answers / Re: Interface for wannier90

« on: January 22, 2016, 14:05 »

Thanks, Anders.  I am trying out NEGF in ATK as well. 

I was able to generate a plot for the basis functions using the basis set tab in script generator.  Can you kindly elaborate a little more on how to do it using a python script. Sorry, I am a still a novice in python (and ATK as well)

Thanks.

3

General Questions and Answers / Re: Interface for wannier90

« on: January 21, 2016, 11:59 »

Hi, Anders Thanks for the reply. 

I just wanted to know if we can find  the  co-ordinates and the distance between two LCAO function centers in quantamwise. I have used a DoubleZeta DoublePolarized basis set for ATK-DFT calculation.  Also is it possible to know the spread of these basis functions.

My final aim is to run a NEGF simulation using the tool NanoTcad vIDEs .

4

General Questions and Answers / Interface for wannier90

« on: January 20, 2016, 20:34 »

Hi,
I did a simulation for a silicon nanowire unit cell , to optimize the geometry and to get the Band structure  . The simulation converged and now I need to get the Maximally Localized Wannier Functions; for which I am trying to run Wannier90.

I am aware of the option to export the .nc files as input for PW in Quantum Espresso to which I can interface Wannier90 and extract MLWFs. But is there anyway I can generate the input file (seedname.win) for Wannier90 using the calculations already done in Quantumwise; without having to run the Self-consistent calculation all over again using Quantum Espresso as the SCF calculation is taking a lot of time.

Waiting to hear from you. Thanks

Dibakar

5

General Questions and Answers / Extracting the hamiltonian for an unit cell of a Nanowire

« on: November 7, 2015, 20:35 »

Hi,

I am new to Quantumwise and as a part of my research work I need to construct  a germanium nanowire oriented in <110> direction. To this end, I have gone through the tutorials for Silicon and InAs nanowires.

 Can someone suggest a way to construct a nanowire oriented in some arbitrary directions for any general material and also how to extract the tight-binding hamiltonian for an unit cell of such a nanowire. Thanks in advance.

Regards,
Dibakar