[Pw_forum] Young's Modulus

[mohsen modaresi]

Dear Eduardo Ariel Menendez Proupin,
I forget to answer other questions.
If we relaxed the tube after compression there is no net force on carbon
atoms so I did not relax the system after compression.
*Have you used a finite nanotube and computed the forces upon the atoms of
the edge?*.....> A finite nano-tube? I consider a unit cell (which can make
an infinite tube ) and calculate force between atoms.
Is there any problem?

Mohsen Modarresi

On Thu, Sep 23, 2010 at 1:21 AM, mohsen modaresi
<modaresi.mohsen at gmail.com>wrote:

> Dear Eduardo Ariel Menendez Proupin,
> At first i relaxed nano-tube and obtain the position of carbon atoms in the
> ground state. Then i decrease the tube length. A in the relation is the area
> of nano-tube (A=pi*R*R which R is the radius of tube). F is the atomic force
> in the Z axis which can be calculated by using Q.E.
> I think it is better to calculate total energy in some configuration and
> use (F=dE/dz, where E is the total energy in different configuration).
> Is there any problem in this procedure?
>
>
>
> On Thu, Sep 23, 2010 at 12:58 AM, Eduardo Ariel Menendez Proupin <
> eariel99 at gmail.com> wrote:
>
>> Hi,
>> I think we always know what WE do, but not all of what computers do :-(.
>>
>> Mohsen, did you relaxed the atoms after the compression? Why did you
>> calculate force and not stress. Have you used a finite nanotube and computed
>> the forces upon the atoms of the edge? Finally, how is defined A in   E=(F/A)/((L-L0)/L0)
>> for the case of a single nonotube?
>> Best regards
>> Eduardo
>>
>> Eduardo Menendez
>> Departamento de Fisica
>> Facultad de Ciencias
>> Universidad de Chile
>> Phone: (56)(2)9787439
>> URL: http://fisica.ciencias.uchile.cl/~emenendez<http://fisica.ciencias.uchile.cl/%7Eemenendez>
>>
>> Let's pray for the 33 trapped miners! Four months to rescue
>>
>>
>>
>>> ---------- Mensaje reenviado ----------
>>>
>>> From: Stefano Baroni <baroni at sissa.it>
>>>  To: PWSCF Forum <pw_forum at pwscf.org>
>>> Date: Wed, 22 Sep 2010 19:43:15 +0200
>>>
>>> Subject: Re: [Pw_forum] Young's Modulus
>>> For that, also LRT akkows one to know what one is doing ... ;-)
>>> SB
>>>
>>> On Sep 22, 2010, at 7:30 PM, Mehmet Topsakal wrote:
>>>
>>> Dear Eyvaz,
>>>
>>> I think you omitted one more thing to mention. Brute-force method also
>>> allows one to know what he is doing.
>>>
>>>
>>>
>>> On Wed, Sep 22, 2010 at 8:14 PM, Eyvaz Isaev <eyvaz_isaev at yahoo.com>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> Yes, you are right about Abinit for elastic constants calculations. The
>>>> main question is which method (Abinit or via total energy) is easier
>>>> and less time-consuming.
>>>>
>>>> Bests,
>>>> Eyvaz.
>>>> -------------------------------------------------------------------
>>>> Prof. Eyvaz Isaev,
>>>> Department of Physics, Chemistry, and Biology (IFM), Linkoping
>>>> University, Sweden
>>>> Theoretical Physics Department, Moscow State Institute of Steel &
>>>> Alloys, Russia,
>>>> isaev at ifm.liu.se, eyvaz_isaev at yahoo.com
>>>>
>>>
>>>>
>> --
>>
>>
>> .
>>
>>
>> _______________________________________________
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>> Pw_forum at pwscf.org
>> http://www.democritos.it/mailman/listinfo/pw_forum
>>
>>
>
>
> --
> Mohsen Modarresi,
> PhD student of Solid State Physics, Ferdowsi University of Mashhad, Iran.
> Phone +98-9133452131
>
>


-- 
Mohsen Modarresi,
PhD student of Solid State Physics, Ferdowsi University of Mashhad, Iran.
Phone +98-9133452131
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