Fwd: Questions about Aestimo 1D

[Zbigniew Koziol]

Dear Run Hu,

My contribution to Aestimo was very small. Now, I am in a different field of activity. I do not remember well how Aestimo works.
Therefore, I am forwarding your message to others who did much more and likely will be able to help you.

Regards,
and best to you.

zb.


-------- Forwarded Message --------

Subject:	Questions about Aestimo 1D
Date:	Mon, 23 Oct 2017 20:46:22 +0900
From:	Run Hu <run....@gmail.com>
To:	soft...@gmail.com

Dear Dr. Koziol,

My name is Run Hu, a postdoc from Tokyo University. Recently, I used your software Aestimo 1D to calculate the electron and hole wavefunction overlap of GaN/AlN MQW system. 

The band energy and the wavefunctions of the first energy states are shown below. Red curve is the wavefunction of electron, and the blue one is for the hole. 

May I ask you for some questions?

1. It seems the strain effect is not considered in your code. Right?

2. When the barrier is thick enough, the confined hole energy and wavefucntions will be recorded in the states_h_QW2.dat and wavefunctions_h_QWR2.dat. But they are not corresponding to each other, especially the wavefunctions. How to solve this problem?

Thanks for sharing your code. 

Best wishes!

I am looking forward to hearing from you.

Run Hu

[h.h...@yahoo.fr]

Hi Run Hu,
I am glad you are using aestimo, here are some answers.

1. Strain effect is included otherwise you will not see the piezo-electric effect (stark effect) because their calculation is linked together in the code.

2. You may check config.py file and set anti_crossing_length to a minimum value (less than smallest barrier thickness ) that may solve the problem.

To enable both stain and piezo effects in config.py see those lines:
"
# Aestimo_numpy_h
anti_crossing_length=1 # the lower length limit to consider anti-crossing (nm)
strain =False # for aestimo_numpy_h
piezo=True # directly calculating the induced electric field.
#--------------
"

I included a test for both cases with and without strain, see the attached figures.

Best regards
Hamza

--------------------------------------------
En date de : Lun 23.10.17, Zbigniew Koziol <soft...@gmail.com> a écrit :

Objet: Fwd: Questions about Aestimo 1D
À: aestim...@googlegroups.com, run....@gmail.com
Date: Lundi 23 octobre 2017, 17h24

[h.h...@yahoo.fr]

Dear Dr. Run,

I will try to answer the last two Emails here. First, aestimo_h calculate conduction and valence bands at the same time but each has its Hamiltonian, so you don't have to invoke both codes (this explains the flat bands in conduction case since aestimo_e does not include piezo-electric effect and do not support MQW).

Secondly, the resulted wave functions (WF) are shifted (for plotting sake) with the value of its corresponding energy state in the plotting section (you sow the test i sent before, they were correctly confined) but in ".dat" files we stored the wave functions as calculated free from any shifts (it will take me time to fix it for you) but if you are using external plotter you can shift each WF with its energy state since they are saved in the same order.

Thirdly, there are two options in setting the number of both electrons and holes states depending on your anti_crossing_length :

1. If you are using one Hamiltonian for all QWs (anti_crossing_length>>Barriers) then the number is multiplied by the number of wells in the structure.
2. Else if you are using for each well its own Hamiltonian (anti_crossing_length<<Barriers) then the number is directly set for one well and it is the same for others.

Ps: i will work on new output files that resemble the plotted ones.

Best regards
Hamza

[h.h...@yahoo.fr]

Dear Dr. Run,
This is from the file VBHM.py.

"""
We consider the upper 3 × 3 Hamiltonian for a (001)-oriented zinc blende (ZB) crystal see ref [1], after block diagonalization the KP-FDM (k.P theory + Finite Difference Method ) method is explained in ref [2] to ensure the Hermitian property of Hamiltonian you have to apply, we have to write all operators of the form presented in ref [3], to understand Hermiticity property see ref [2]. page 110, same code in Fortran language presented in the index of ref [1]. Dirichlet boundary conditions were applied [1].

[1]:D.Ahn & S-H.Park 'ENGINEERING QUANTUM MECHANICS' P 238
[2]:P.Harrison 'QUANTUM WELLS, WIRES AND DOTS' P 357-362
[3]: S-L.CHUANG 'physics of Optoelectronic Devices' P 183
"""
Best regards
Hamza
--------------------------------------------
En date de : Jeu 26.10.17, Run Hu <run....@gmail.com> a écrit :

Objet: Re: Re : Fwd: Questions about Aestimo 1D
À: h.h...@yahoo.fr
Date: Jeudi 26 octobre 2017, 15h15

Dear Dr. Hebal,
Thanks for helping!
Problem's solved. 

Do you have any papers or
reference documents about how the code works to solve
Schrodinger-Poisson self-calculation?
It is said that "This is the
3x3 k.p aestimo calculator for valence band
calculations". Right?
Finally, thanks very very
much!
Best
Run 

On 26 October 2017 at
22:17, <h.h...@yahoo.fr>
wrote:
Dear Dr.
Run,

Problem solved, you will find both results of electrons and
holes in the same directory, thank you for pointing that
out.

Best regards

Hamza

------------------------------ --------------

En date de : Jeu 26.10.17, Run Hu <run....@gmail.com>
a écrit :



 Objet: Re: Re : Fwd: Questions about Aestimo 1D

 À: h.h...@yahoo.fr

 Date: Jeudi 26 octobre 2017, 9h52



 Dear Dr. Hebal,

 Thanks for your reply. In

 fact, I use the latest version of Aestimo 1.1.0. 

 After setting

 anti_crossing_length=1 and modifying the config.py to
the

 desired input file, we simply run command like:

 ./aestimo_h.py , it will soon generate the directory

 outputs_h. As the figure shows below.

 In the outputs_h directory,

 I can access the wavefucntion and states for holes. But
I

 still don't find the wavefunctions and states for

 electrons. I don't why. Could you help to solve

 this?

 Attached please find the

 config.py and input file. 

 Thanks very

 much.

 Run









 On 26 October 2017 at

 04:18,  <h.h...@yahoo.fr>

 wrote:

 Dear Dr.

 Run,







 I think you are using an old version of Aestimo, you
can

 find the atest version of Aestimo  v.1.1 here:



 http://www.aestimosolver.org



 Here is a direct link:



 https://github.com/

 sblisesivdin/aestimo/archive/ master.zip



 Go download this version and just execute the multi-qw

 sample (the same you are asking for), it works just
fine

 (just set anti_crossing_length=1 in config.py file).



 Again the ".dat" files where you find energy

 levels and wave function are not set to plot together,
I

 will try to fix that soon.



 Try it and tell me.



 Best regards



 Hamza















 ------------------------------ --------------



 En date de : Mer 25.10.17, Run Hu <run....@gmail.com>

 a écrit :







  Objet: Re: Re : Fwd: Questions about Aestimo 1D



  À: h.h...@yahoo.fr



  Date: Mercredi 25 octobre 2017, 18h53







  Dear



  Dr. Hebal,



  Thanks



  very much for your kind reply. 



  The



  first question bothers me a lot. I also try the

 aestimo_h



  only, but I cannot get the wavefunction and states
for



  electrons. Only the wavefucctions and states for
holes

 will



  be generated. 



  Could



  you kindly send me your input file to calculate the

 electron



  and hole simultaneously?



  Best



  wishes!



  Run



  On 26 October 2017 at



  02:38,  <h.h...@yahoo.fr>



  wrote: