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Messages - rahulprajesh

Pages: [1] 2
1
General Questions and Answers / Re: geometric constraint
« on: May 20, 2011, 15:43 »
No, there are only 68 atoms in the central region that you can constrain.

But wait, is this for ATK 11.2? The system can't be valid in 11.2, if you have fewer atoms in the central region than in the two electrodes combined (see here).

So something is wrong here.

but sir the indices i mentioned here belong to the central region so why it's not correct ?

2
The amount of memory needed for a calculation depends on very many factors. However the general rule is that if you have problems with memory not being enough, take care to only assign one MPI process per physical node on the cluster, and also make sure you have that node to yourself, otherwise other programs might run on it and limit the available RAM.
Sir i've six core processor 3.0Ghz, 12Gb of memory isn't it sufficient ???

3
General Questions and Answers / Re: geometric constraint
« on: May 20, 2011, 11:56 »
You shouldn't count the electrode atoms. Since you are only relaxing the central region, the constraints refer to these atoms only. Yes, the indices correspond to the atoms, in the order they appear in the geometry definition.
so should i put it like--- range(36,53)+range(86,139) ?
----
one more doubt if leave the geometric constraint(VNL) text box blank what does it mean.?
----

4
This error is frequently reported, but the only way it can arise is that the machine runs out of memory. If you are running the calculation in parallel, and placing several MPI processes on the same machine, you will quickly ramp up the memory usage since each process uses the same amount of memory.

Sir in that case which Computer configuration would be sufficient ? Tell me what should be the memory n processors?

5
General Questions and Answers / geometric constraint
« on: May 20, 2011, 11:01 »
Sir,
i've a two probe system with 36(left electrode)+(18+32+18)-central Region + 36(right electrode)
i want to constraint the electrode as well as electrod element in scattering region(as recommended in tutorials). i tried with
 geometric_constraints = range(0,53)+range(86,139)
it shows error ------ saying indices can't be more than 68.
--------------------------
tell me if my syntax is right or wrong ??
--------------------------

and one more thing is the indexing order same how they appear in script ?
--------------------------
Thank you.

6
General Questions and Answers / ivcurve error
« on: March 10, 2011, 04:31 »
hello Sir,
i'm getting this errror . what is the problem. ?
Traceback (most recent call last):
  File "xyz_iv.py", line 59, in ?
    current_number_of_points = 100
  File "ivcurve.py", line 80, in runIVcurve
    if processIsMaster(): f.addToSample(current,sample_name,'Current at %s V bias' % voltage.inUnitsOf(Volt))
TypeError: addToSample() takes exactly 3 arguments (4 given)

7
General Questions and Answers / Re: ATKError: bad allocation
« on: March 5, 2011, 22:34 »
The following parameters should be checked for each configuration because they could strongly affect the required memory size:
i). How many atoms are included in your two different configurations (i.e.,normal size and supercell one)?
ii). What kind of basis set is used? DZP, SZP, or others?
iii). What size is used for the k-point grid? i.e., how many k points are used?
iv). What is the value of the mesh cutoff?

In additional, the nearest neighbor (NN) distances between atoms should also be checked. If one of the NN distances is too short, i.e., two atoms are very close or even overlapped, the job would fail.

Hello ,
m also getting the same error while simulating my structure can anybody help me out. My script file is attached here.

8
Hi everybody two probe configuration of AU CNT AU IV characteristics are same as the cntfet IV characteristics.i mean two probe configuration is acts like cntfet or not ,if yes explain how.
hey jagan hi,,,
probing CNT is interesting. Can  u tell me how you probed a CNT? ..
if possible tell me size of ur electrode and CNT .
i want to learn how CNT behvs,,,,!!
Thanks,.

9
General Questions and Answers / Re: size of Electrodes
« on: March 2, 2011, 14:42 »
There should be no limit however you must have enough memory to handle the system on your machine in order to perform a calculation on it.

Depending on the number of atoms in your electrode before you perform the repetition, it might require somewhat of your graphics card to draw all the atoms. On my machine I can easily have 3000 atoms in the bulk builder.

Thanks Sir,
i'll try on some other Machine....

10
General Questions and Answers / size of Electrodes
« on: March 2, 2011, 08:55 »
hello,

can anybody tell me what is the maximum size of an electrode i can make using quantumwise.
i mean to say what is maximum limit for repetition option given in Bulk Builder ?
It doesn't respond for value more than 10.

Thanks...

11
When I enable the gate in two probe setup and provide the value to gate no units are mentioned, how do I know the magnitude of gate potential? Also if I want to change the potential by one electron volt what is the method?
The units of Gate potential are Volts and now its not difficult to change the value by 1 volt (its 1 volt not 1 electron volt as you are taking potential)

12
Go through this tutorial it will help  you understand bulk builder and atomic manipulator tool for designing shaped electrodes.

http://www.quantumwise.com/documents/tutorials/Tutorial_GoldMonowire.pdf

13
I think Sir if we Can Use Formation Energy instead of Total energy it will serve My purpose because change in enthalpy of a reaction uses:: (sum of Formation energies of Products - sum of formation energies of reactants)..Now the problem is how to calculate the formation energy???

14
dear Sir, I've proceeded in the same way as you indicated...
         and used the DZP(Basis Set) With GGA.pbe.
                    But Still  My result is far away from experimental values like I laso tried to calculate c-h bond dissociation energy for c-h bond in c2h6 ..and got a value = 6.5195 eV (experimatal is=4.40625eV)
i dont know where is the problem and why its not working. help me ????

15
Its a nice script sir ,
                            Is there any way to calculate the particular bond's energy in a molecule like what if we want to calculate for example c-h  bond energy in Methane Molecule how can we do that.
                            thanks Sir

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