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Topics - ph

Pages: [1]
1
General Questions and Answers / Iso value and Band gap
« on: May 2, 2014, 15:34 »

Dear Sir,

1) In case of plotting  Electron difference density along transport direction (in 3D plots), is the ISO value variation(adjustment) dependens on any calculated technical parameters or we can vary as per our wish ?. Please give some details.

2) How to easily  extract (or interpret) band gap from rough edges of  Conduction and valence bands in case of LDDOS plotted along transport direction.?


 Kind Regards



2
General Questions and Answers / Turning off threading in multinode cluster
« on: April 1, 2014, 15:22 »
Dear Sir,
To speedup the calculation using ATK in a multi node cluster environment is it necessary to turn off threading?. If it is so, is it  to turn off every node in a cluster or turning off only in master node?. waiting for your kind advice.

3
Installation and License Questions / How to parallelize two processors on Ubuntu server
« on: August 23, 2013, 14:35 »
Dear Sir,
We installed server with Ubuntu 12.0.4 LTS  server package with mpich2. We also installed ATK on server. It is having two processors each with 8 cores. How to make use of  two processors with 16 cores. What is the mpi command to run ATK in parallel ?. which client package (like vnc, putty.. ssh..)    is better to connect  server for accessing ATK from server. Kindly help.

kind Regards
 


4
General Questions and Answers / How to plot Potential energy vs Distance in transport direction plot
« on: August 13, 2013, 07:44 »
Dear Sir,

To plot Energy Band (gap)profile vs Distance along  PN junction(in transport direction) is there any option in VNL?. Or any useful script?. Similarly  for LDOS vs Distance.Kindly help.

Kind Regards

5
General Questions and Answers / Is it transvers average transmission or total transmission ?
« on: July 11, 2013, 14:52 »
Dear Sir,

I performed transport calculation and obtained transmission spectrum for my 2D sheet(x-z plane) and . The relevant script is as follows.

transmission_spectrum = TransmissionSpectrum(
    configuration=device_configuration,
    energies=numpy.linspace(-2.0, 2.0,401)*eV,
   kpoints=MonkhorstPackGrid(23,1),

energy_zero_parameter=AverageFermiLevel,
    infinitesimal=1e-06*Units.eV
    )
 
What kind of transmission is it giving? Is it only Longitudinal  transport along Z-direction? or  Average transverse transport along X-direction? or  Sum of both longitudinal and transverse transport?

2) What modification do I need, If I want to have transmission spectrum or current only in transverse direction?

3) How to get(or combined) total current(sum of longitudinal and transverse)?    or total transmission spectrum?

Kind regards
 

6
General Questions and Answers / What is the role of energy points in a transmission spectrum?
« on: May 28, 2013, 15:54 »
Dear Sir,
energies=numpy.linspace(-0.8,0.8,401)*eV,

I plotted transmission Spectra with (infinitesimal=1e-9) different number of energy points in given range in a particular direction but every time only particular peaks  are varying. What is the role of increasing and decreasing number of energy points in a given transmission spectrum. As the number of points increasing the peaks also increasing. Where to stop number of points? Which plot is reasonably correct?.  Kindly see attached.

regards

7
General Questions and Answers / How to plot normalized Transmission vs Energy[eV] graph
« on: May 27, 2013, 15:14 »
Dear Sir,
Is there any option in VNL to plot normalized transmission spectrums?. If not what additional python script do we add to achieve the same?

Regards
 

8
General Questions and Answers / How to plot Conductance[2q2/h] vs Energy[eV] graph
« on: May 22, 2013, 11:47 »
Dear Sir,
I have transmission spectrum for my 2D Transport structure. From Transmission spectrum is there any way to plot  Conductance[2q2/h] vs Energy[eV] graph?. Kindly show me the  option from VNL or any custom script.

Regards


9
Installation and License Questions / Clustering few machines
« on: August 30, 2012, 16:52 »
Dear Sir,
1) I have  an  ATK12.2.2  license of 2 masters and 6 slaves, with this how many machines(each with 4 cores) I can cluster with good performence ?. I am using Ubuntu linux11.04 with mpi. All machines are  now in network.

2) With our license, Is it possible to run, the same file in multiple machines by make use of more cores to save time?. Running one input file in one machine(with 4 cores) is faster ? or running the same on multiple machines is faster, by make use of more cores ?
3) If it is possible, how to address  all the  machines and their cores using mpi. Kindly give command syntax?

 My license configuration is as follows:

FEATURE atkmaster
{
VENDOR = QUANTUM
COUNT = 2
VERSION = 12.8
KEY = --------------------
}

FEATURE atkslave
{
VENDOR = QUANTUM
COUNT = 6
VERSION = 12.8
KEY =---------------------------    
}
FEATURE vnl
{
VENDOR = QUANTUM
COUNT = 2
VERSION = 12.8
KEY =---------------------------------    
}
FEATURE atkdft
{
VENDOR = QUANTUM
COUNT = 1000
VERSION = 12.8
KEY = -----------------------
}
------------
--------------
----------------
I am waiting for your kind reply.



10
General Questions and Answers / Calculator settings for transport properties of 2d Graphene and 1D nanoribbon
« on: August 7, 2012, 15:24 »
Dear Sir,
Can I use (similar pattern) calculator settings for 2D graphene transport  (Electrode 1x1x50  and  central region 1x1x50 ) and 1D graphene nanoribbon(  Electrode 1x1x50  and  central region 1x1x50) like this? or  for 2D transport is there any other pattern needed?. Or this is depends on any other issues?.

Kind regards



11
General Questions and Answers / How to accurately calculate Density of States(DOS) for 2D systems
« on: March 20, 2012, 18:09 »
Dear Sir,
1)To calculate DOS, whether we have to keep  the k-points in the DFT calculator (e.g,13X13X1) and  in the k-points in the DOS analysis function(e.g,13X13X13) are same or different?
2)For the  above 2D system, if we  want to calculate Band structure and DOS, is it necessary to maintain same k-points for Band structure and DOS ?
3) What is the influence of points per segment in DFT-calculator on Band structure and DOS?
4)What is the importance of Projected DOS for a given system? or When we need to use PDOS?
5)What are  the general  thumb rules for  calculating accurate DOS of a system?

Best Regards
Ph       

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