[Pw_forum] Relaxed Graphene Nanoribbon

Arles V. Gil Rebaza arvifis at gmail.com
Tue May 10 03:03:05 CEST 2011


About the relationship between the reciprocal and real spaces, you can find
in some book of Solid State, authors like Ashcroft or Kittel. In order to
select the number of k-points you need to do convergence of the total energy
(or your observable) respect the number of k-points...!!! The same criteria
to select the optimal value of cut-off energy and perhaps also for the
length of the third vector (z direction) because you should consider the
periodicity of QE.

Best.

PhD std. Arles V. Gil Rebaza
Instituto de Física de La Plata
La Plata-Argentina


2011/5/9 swapnil chandratre <swapnil.chandratre at gmail.com>

> Hello,
>
>
> Thank you all for your responses, I was using a software to generate the
> geometry of ribbon, it gave me the data regarding the *unit cell *dimensions
> so I just transfered the data from there. And when I visualized it there, it
> seemed to be perfect, I am trying to install XCrysden so that I can avoid
> such issues again.
>
> Arles, can you shed some knowledge on how to go for the k points, as it is
> 1d,I assume 100 k points may be sufficient to give reasonable idea, I just
> randomly selected 25 as a starting point, and can anyone suggest any reading
> material or approach towards defining the cut off energies and K points.
>
> Thank you.
>
> On Mon, May 9, 2011 at 9:44 AM, Arles V. Gil Rebaza <arvifis at gmail.com>wrote:
>
>> Your unit cell vectors are wrong, because many atoms positions are out the
>> unit cell..!! futhermore, why do you put 25 1 1 k-points...?? remember that
>> the reciprocal space is inversely proportional to real space....!!!
>>
>> Best.
>>
>> PhD std. Arles V. Gil Rebaza
>> Instituto de Física de La Plata
>> La Plata-Argentina
>>
>>
>> 2011/5/9 mousumi uk <larikamonu at gmail.com>
>>
>>> Your unit cell is wrong.... visualize your structure in xcrysden and
>>> correct the CELL_PARAMETERS.
>>>
>>> Best regards,
>>> Mousumi
>>>
>>> On Mon, May 9, 2011 at 6:36 AM, swapnil chandratre <
>>> swapnil.chandratre at gmail.com> wrote:
>>>
>>>> Hi,
>>>>
>>>> I have prepared an input file for a porous graphene nanoribbon, can
>>>> anyone please comment if there are any errors with the file.
>>>>
>>>> &control
>>>>     calculation  = 'relax'
>>>>     restart_mode = 'from_scratch'
>>>>     pseudo_dir    = '/home/s/schandratre/Espresso/pseudo'
>>>>     outdir        = '/home/s/schandratre/Espresso/run'
>>>>
>>>>  /
>>>>  &system
>>>>
>>>>     ibrav = 0
>>>> nat=96
>>>> ntyp=2
>>>> ecutwfc=80.0
>>>> ecutrho = 600.0
>>>> occupations = 'smearing'
>>>> degauss=0.02
>>>> smearing = 'gaussian',
>>>>  /
>>>>  &electrons
>>>>     conv_thr = 1.0d-6,
>>>>     mixing_beta=0.3,
>>>>   /
>>>> &ions
>>>> ion_dynamics='damp'
>>>> pot_extrapolation='second_order'
>>>> wfc_extrapolation='second_order'
>>>> /
>>>>
>>>> ATOMIC_SPECIES
>>>> C 12.0000 C.pz-rrkjus.UPF
>>>> H 1.00000 H.pz-rrkjus.UPF
>>>>
>>>> ATOMIC_POSITIONS {angstrom}
>>>>   C   2.841720  5.953494  5.000000
>>>>   C   3.552150  7.183995  5.000000
>>>>   C   1.420860  5.953494  5.000000
>>>>   C   2.841720  8.414496  5.000000
>>>>   C   3.552150  9.644997  5.000000
>>>>   C   0.710430  7.183995  5.000000
>>>>   C   1.420860  8.414496  5.000000
>>>>   C   2.841720  10.87550  5.000000
>>>>   C   3.552150  12.10600  5.000000
>>>>   C   0.710430  9.644997  5.000000
>>>>   C   1.420860  10.87550  5.000000
>>>>   C   2.841720  13.33650  5.000000
>>>>   C   3.552150  14.56700  5.000000
>>>>   C   0.710430  12.10600  5.000000
>>>>   C   1.420860  13.33650  5.000000
>>>>   C   0.710430  14.56700  5.000000
>>>>   H   3.392220  5.000000  5.000000
>>>>   H   0.870360  5.000000  5.000000
>>>>   H   3.001650  15.52049  5.000000
>>>>   H   1.260930  15.52049  5.000000
>>>>   C   7.104300  5.953494  5.000000
>>>>   C   7.814730  7.183995  5.000000
>>>>   C   5.683440  5.953494  5.000000
>>>>   C   7.104300  8.414496  5.000000
>>>>   C   4.973010  7.183995  5.000000
>>>>   C   5.683440  8.414496  5.000000
>>>>   C   7.104300  10.87550  5.000000
>>>>   C   7.814730  12.10600  5.000000
>>>>   C   4.973010  9.644997  5.000000
>>>>   C   5.683440  10.87550  5.000000
>>>>   C   7.104300  13.33650  5.000000
>>>>   C   7.814730  14.56700  5.000000
>>>>   C   4.973010  12.10600  5.000000
>>>>   C   5.683440  13.33650  5.000000
>>>>   C   4.973010  14.56700  5.000000
>>>>   H   7.654800  5.000000  5.000000
>>>>   H   5.132940  5.000000  5.000000
>>>>   H   7.264230  15.52049  5.000000
>>>>   H   5.523510  15.52049  5.000000
>>>>   C   11.36688  5.953494  5.000000
>>>>   C   12.07731  7.183995  5.000000
>>>>   C   9.946020  5.953494  5.000000
>>>>   C   11.36688  8.414496  5.000000
>>>>   C   12.07731  9.644997  5.000000
>>>>   C   9.235590  7.183995  5.000000
>>>>   C   11.36688  10.87550  5.000000
>>>>   C   12.07731  12.10600  5.000000
>>>>   C   11.36688  13.33650  5.000000
>>>>   C   12.07731  14.56700  5.000000
>>>>   C   9.235590  12.10600  5.000000
>>>>   C   9.946020  13.33650  5.000000
>>>>   C   9.235590  14.56700  5.000000
>>>>   H   11.91738  5.000000  5.000000
>>>>   H   9.395520  5.000000  5.000000
>>>>   H   11.52681  15.52049  5.000000
>>>>   H   9.786090  15.52049  5.000000
>>>>   C   15.62946  5.953494  5.000000
>>>>   C   16.33989  7.183995  5.000000
>>>>   C   14.20860  5.953494  5.000000
>>>>   C   15.62946  8.414496  5.000000
>>>>   C   16.33989  9.644997  5.000000
>>>>   C   13.49817  7.183995  5.000000
>>>>   C   14.20860  8.414496  5.000000
>>>>   C   15.62946  10.87550  5.000000
>>>>   C   16.33989  12.10600  5.000000
>>>>   C   13.49817  9.644997  5.000000
>>>>   C   14.20860  10.87550  5.000000
>>>>   C   15.62946  13.33650  5.000000
>>>>   C   16.33989  14.56700  5.000000
>>>>   C   13.49817  12.10600  5.000000
>>>>   C   14.20860  13.33650  5.000000
>>>>   C   13.49817  14.56700  5.000000
>>>>   H   16.17996  5.000000  5.000000
>>>>   H   13.65810  5.000000  5.000000
>>>>   H   15.78939  15.52049  5.000000
>>>>   H   14.04867  15.52049  5.000000
>>>>   C   19.89204  5.953494  5.000000
>>>>   C   20.60247  7.183995  5.000000
>>>>   C   18.47118  5.953494  5.000000
>>>>   C   19.89204  8.414496  5.000000
>>>>   C   20.60247  9.644997  5.000000
>>>>   C   17.76075  7.183995  5.000000
>>>>   C   18.47118  8.414496  5.000000
>>>>   C   19.89204  10.87550  5.000000
>>>>   C   20.60247  12.10600  5.000000
>>>>   C   17.76075  9.644997  5.000000
>>>>   C   18.47118  10.87550  5.000000
>>>>   C   19.89204  13.33650  5.000000
>>>>   C   20.60247  14.56700  5.000000
>>>>   C   17.76075  12.10600  5.000000
>>>>   C   18.47118  13.33650  5.000000
>>>>   C   17.76075  14.56700  5.000000
>>>>   H   20.44254  5.000000  5.000000
>>>>   H   17.92068  5.000000  5.000000
>>>>   H   20.05197  15.52049  5.000000
>>>>   H   18.31125  15.52049  5.000000
>>>>
>>>> CELL_PARAMETERS
>>>> 19.200000 0.000000 0.000000
>>>> 0.0000000 21.90350 0.000000
>>>> 0.0000000 0.000000 10.00000
>>>>
>>>> K_POINTS {automatic}
>>>>  25 1 1  0 0 0
>>>>
>>>>
>>>> --
>>>> Regards,
>>>> Swapnil Chandratre
>>>> Graduate Student
>>>> Dept. of Mechanical Engineering,
>>>> University of Houston,
>>>> Houston, TX
>>>> (M)-713-294-9546
>>>>
>>>> _______________________________________________
>>>> Pw_forum mailing list
>>>> Pw_forum at pwscf.org
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>>>>
>>>>
>>>
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>>>
>>
>>
>> --
>> ###--------->   Arles V.   <---------###
>>
>> _______________________________________________
>> Pw_forum mailing list
>> Pw_forum at pwscf.org
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>>
>>
>
>
> --
> Regards,
> Swapnil Chandratre
> Graduate Student
> Dept. of Mechanical Engineering,
> University of Houston,
> Houston, TX
> (M)-713-294-9546
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>


-- 
###--------->   Arles V.   <---------###
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