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Messages - njuxyh

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46
General Questions and Answers / why the electron difference density is not consistant with previous study
« on: April 25, 2018, 11:28 »
Dear All:

i consists a MoS2-graphene hetero structures using the Interface tool in the Builder option.The parameters chosen are shown in figure 1. the relaxed geometry is a=6.321,b=6.321,c=24.804. the distance between Gr and Mos2 is 3.34 angstrom.
the relaxed configuration  py file are attached.
and we noticed that in our configurations, one C atoms of Gr is located uopn the S atom in mos2. so we though it is very close to TS configuration presents in the Nanoscale, 2011, 3, 3883–3887.

but we plot the electron difference density, and found it is NOT consistent with that in eNanoscale, 2011, 3, 3883–3887. the different details are show in figure 2 and figure 3

so i am wondering what is the reason make the electron difference density different, especially the C layer lost electrons while in our calculation C  get electrons.
 
i need your help.

 
thanks a lot

47
General Questions and Answers / Re: how to acesss "how to simulate interfaces in electronics at the atomic scale"
« on: April 25, 2018, 10:14 »
thank you  very much .

i saw the news.

best wishes

48
General Questions and Answers / how to acesss "how to simulate interfaces in electronics at the atomic scale"
« on: April 7, 2018, 13:41 »
Dear Sir:

i am interesting the webinar,"how to simulate interfaces in electronics at the atomic scale",  but i missed the time, so i am woundering is there any recordings to access?

thank you very much


49
General Questions and Answers / how to convert the interface cell into orthorhombic cell for electrode usage
« on: February 2, 2018, 06:55 »
Hi :

I have built an interface, and the cell is chosen as unit cell (see figure1)with
a=14.704
b=5.47397
c=11.395
alfa=43.8979degree
beta=90 degree
gama=90 degree
because the cell is most stainless, about 4.1%.
as it knows, if I build the interface as an electrode, the cell should be an orthorhombic cell. I used the ''supercell'' option and choose based (body or face) orthorhombic.but it cannot be made to the orthorhombic cell at all. the option ''device from bulk"
so I am wondering how I can make it as an electrode.







50
General Questions and Answers / Re: Question about building interface model
« on: February 1, 2018, 09:40 »
Dear Professor Blom:

because i want to construct an interface in which one of the layers rotated 30%. so would you please tell me how to build, because I cannot find the  Cf. http://quantumwise.com/publications/tutorials/builder/179-commensurate-supercell-for-rotated-graphene-layers.




Quote from: Anders Blom on July 21, 2013, 23:24
1. The "default" model is the one with the lowest number of atoms and the smallest strain, but since these two parameters are in opposition to each other in many cases, it's supposed to be some compromise. One had better not just blindly accept the model, but check the strain (and indeed the surface shifts) very carefully.

2. There may be some possible matches that are missed, but they may also be "hidden" since several model may have very similar strain and atom numbers, so the plot points end up on top of each other. You can always make your own model by pulling the red and blue arrows in the surface plots at the top!

The algorithm is called the surface coincidence method and just tries all possible rotations and linear combinations of the two sets of lattice vectors. There is however a certain resolution, which can be changed if you know already that you are looking for a particular angle (or at least an angle in a particular interval). Cf. http://quantumwise.com/publications/tutorials/builder/179-commensurate-supercell-for-rotated-graphene-layers.



Cf. http://quantumwise.com/publications/tutorials/builder/179-commensurate-supercell-for-rotated-graphene-layers.

51
General Questions and Answers / Re: bulk InSe band gap is wrong in the 2017.a2 version
« on: June 2, 2017, 09:59 »
yes, the optimized lattice is not the same using two different version,  in older 13.8.1 version, i used QuasiNewton method. but  the newest 17.a2 version i used LBFGS.

So i am wondering why 17.a2  and 13.8.1 give so much different lattice constant.

52
General Questions and Answers / Re: bulk InSe band gap is wrong in the 2017.a2 version
« on: May 31, 2017, 14:41 »
yes, i used "normconserving/SE.GGAPBE.zip in the 13.8.1

53
General Questions and Answers / Re: bulk InSe band gap is wrong in the 2017.a2 version
« on: May 30, 2017, 10:09 »
thank you for your kindly reply.

yes, i confirmed that the bulk inse is semiconductor, please go to the material project web:
https://materialsproject.org/#search/materials/{"reduced_cell_formula"%3A"InSe"}

in fact, i used 2 kpoints in the z direction, unfortunately,the result does not change .

54
General Questions and Answers / bulk InSe band gap is wrong in the 2017.a2 version
« on: May 29, 2017, 09:57 »
Hi all

i tried the newest version 2017.a2 to calculate the band gap of bulk Inse.

I used GGA-PBE. as we know, the local EXC-Function will underestimate the band gap, but my results is opposite, which is 1.35eV, While the experimental value is 0.5eV


i test the calculation with the older version such 13.8.1, the band gap is almost the same with the experimental value.

so i am wondering what cause the error.


please help me.

thanks very much

55
General Questions and Answers / how to choose the R e al a xis p oin t d e n sit y?
« on: September 3, 2016, 15:57 »
Hi all:

I read the following tutorial:   http://docs.quantumwise.com/_downloads/atk_transport_calculations.pdf

NEGF contour integral NEGF contour integral For finite-bias calculations, a potentially important convergence parameter is the R e al a xis p oin t d e n sit y , which is specified under C o n t o u r in t e g r al p a r a m e t e r s . This parameter determines how many energy points are used when integrating the left and right spectral density matrices along the real energy axis between the chemical potentials of the left and right electrodes. For the present calculation you can proceed with the default value, but be aware that a convergence test of this parameter should in general be performed.


so, if the self-consistent calculation of device under bias did not converge?  should I increase the real axis point density to see the results? 

56
General Questions and Answers / the scf of iv-curve in some bias did not convengency, some did converge
« on: August 31, 2016, 04:03 »
Hi :
I calculated the iv-curve under 0-2 V, But I found under 1.4,1.6,0.6,0.4.0.2 V the scf calculation did converge, but other bias point did not converge such 0.8,1.0.1.2 .1.8.2.0.
  217   S   [   3.337 ,  19.732 ,  67.456 ]    6.82742   0.82742              |
|  218   S   [   2.275 ,  23.070 ,  67.460 ]    6.36327   0.36327              |
|  219   S   [   4.364 ,  23.102 ,  67.461 ]    6.36487   0.36487              |
+------------------------------------------------------------------------------+
|  99 E =  -356.72 dE =  3.048208e-04 dH =  1.026967e-02                       |
+------------------------------------------------------------------------------+
################################################################################
#                                                                              #
# Warning: The calculation did not converge to the requested tolerance!        #
#                                                                              #
################################################################################
+------------------------------------------------------------------------------+
|                                                                              |
| NEGF DFT Calculation  [Finished Sat Aug 27 18:33:23 2016]                    |
|                                                                              |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
|                                                                              |
| Device DFT Calculation  [Finished Sat Aug 27 18:33:23 2016]                  |
|                                                                              |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
|                                                                              |
| Transmission Spectrum Analysis                                               |
|                                                                              |
+------------------------------------------------------------------------------+

                            |--------------------------------------------------|
Calculating Transmission   : ==================================================
                                                                                           


 so I am wondering how to set the parameter to continue to recalculated the transmission spectrum under converge bias 0.8,1.0.1.2 and 1.8.2.0 V.
my current calculation only has one checkpoint file which including the whole bias 0-2 V.
 

57
General Questions and Answers / Re: the electrics difference potential （ EDP） of MGGA results are trustfuL or GGA ?
« on: August 31, 2016, 03:03 »
Hi  Daniele Stradi:

according to your states, I thought I  had a poster previous, i asked  MGGA is suitable for the transmission spectrum ?
in my two slab interface mentioned here ? one staff answer me sure,

so i am wondering if MGGA can not give trustful results for ther EDP, then MGGA can give me trustful transmission spectrum?

please help me  make me clear about this issue。


thanks very  much




58
General Questions and Answers / the electrics difference potential （ EDP） of MGGA results are trustfuL or GGA ?
« on: August 29, 2016, 12:05 »
Hi
I am calculated the electrics difference potential with  same interface, but I found the deltV  between  the two  atoms layer is opposite, so I am wondering the MGGA can calculate the EDP？
ps： my interface is two slab, the MGGA c parameter has fixed to some value to fitting the GW gap, and the warning of  MGGA is 
The computed TB09 meta-GGA exchange-correlation potential                    #
# diverged in   0.01 % of the simulation volume, and was                       #
# truncated to be in the range [-10.0000,  10.0000] Hartree   

so I am wounding the MGGA result for the EDP is trustful or GGA results is trustful.

59
General Questions and Answers / the memory usage is too large to complte the iv-calculation
« on: August 27, 2016, 04:18 »
Hi all

I am using ATK 2016, but I found the memory is used too large when I calculated the iv curve under bias, the calculation is always crash.

is there method or setting  to reduce the memory but not to reduce calculation precision during calculation please help me.



 PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
10126 MSI       20   0 7257m 6.6g  35m R 100.0 21.3   1109:38 atkpython                                                                                                                       
10127 MSI       20   0 7348m 6.7g  34m R 100.0 21.5   1109:38 atkpython                                                                                                                       
10125 MSI       20   0 7188m 6.6g  37m R 98.3 21.0   1109:44 atkpython                                                                                                                         
10128 MSI       20   0 7165m 6.5g  37m R 98.3 20.7   1109:43 atkpython     

60
General Questions and Answers / iv-curve calculation stoped with error in atk2016
« on: August 25, 2016, 02:33 »
Hi
i used ATK 2016,  i want to calculated the iv curve at 0~2 V,  using the *.nc at 0 V bias , but the calculation process interupt, the log said:


+------------------------------------------------------------------------------+
|                                                                              |
| Transmission Spectrum Analysis                                               |
|                                                                              |
+------------------------------------------------------------------------------+

                            |--------------------------------------------------|
Calculating Transmission   : ==================================================

+------------------------------------------------------------------------------+
| IV-Curve Calculation                                                         |
+------------------------------------------------------------------------------+
| The current will be calculated at 10 points between 0.000 to 2.000 V.        |
| Note: The current has already been calculated at 0.000 V.                    |
| Each bias point will be calculated using 4/4 MPI processes.                  |
|                                                                              |
| Bias Point  Process Group  Log File                                          |
|      0.200              0  ivcurve_0.20000V.log                              |
|      0.400              0  ivcurve_0.40000V.log                              |
|      0.600              0  ivcurve_0.60000V.log                              |
|      0.800              0  ivcurve_0.80000V.log                              |
|      1.000              0  ivcurve_1.00000V.log                              |
|      1.200              0  ivcurve_1.20000V.log                              |
|      1.400              0  ivcurve_1.40000V.log                              |
|      1.600              0  ivcurve_1.60000V.log                              |
|      1.800              0  ivcurve_1.80000V.log                              |
|      2.000              0  ivcurve_2.00000V.log                              |
+------------------------------------------------------------------------------+
rank 3 in job 5  node11_56242   caused collective abort of all ranks
  exit status of rank 3: killed by signal 11


the outfile only has three :
 ivcurve_0.20000V.log                                                                 
 ivcurve_0.40000V.log                                                                         
ivcurve_0.60000V.log 

i found the above three file, the calculation is not complete, all stopped:

+------------------------------------------------------------------------------+
|                                                                              |
| NEGF DFT Calculation  [Finished Wed Aug 24 16:56:55 2016]                    |
|                                                                              |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
|                                                                              |
| Device DFT Calculation  [Finished Wed Aug 24 16:56:55 2016]                  |
|                                                                              |
+------------------------------------------------------------------------------+
+------------------------------------------------------------------------------+
|                                                                              |
| Transmission Spectrum Analysis                                               |
|                                                                              |
+------------------------------------------------------------------------------+

                            |--------------------------------------------------|
Calculating Transmission   : ==================================================


so i am wondering what happened? is it memory problem?or would i complete my iv  calculation?


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