[QE-users] a silly question to set the volume of the unit cell

Sun Apr 5 15:21:18 CEST 2020

Hi,
please look the following link
https://lists.quantum-espresso.org/pipermail/users/2010-March/016270.html

I suppose you have the same problem, if I understood correctly.

Thanks,
Rita

Rita Maji
Research scholar
School of Physical Sciences
National Institute of Science Education and Research
Bhubaneswar, 752050
Odisha, India

On Sun, Apr 5, 2020 at 12:54 AM rekha sharma <rekha1997jpr at gmail.com> wrote:

> Thank you Sir/Madam,
> It worked for me. I have changed all cell vectors by +/-1%.
>  How I can estimate the %change in the volume?  Or I should ask if I
> change all cell vectors by +/-1% then how the volume will change based on
> these new parameters for monoclinic structure? I see volume is changes by
> around 2-3%. for moclinic case the V is calculated by a*b*c*sin(beta). But
> I am not able to get this volume value from the QE.in file?
> Could you please elaborate it?
>
> -1%
>
> bravais-lattice index = 0
>
> lattice parameter (alat) = 11.5206 a.u.
>
> unit-cell volume = 4358.0284 (a.u.)^3
>
> crystal axes: (cart. coord. in units of alat)
>
> a(1) = ( 1.000000 0.000000 0.000000 )
>
> a(2) = ( -0.471829 1.069357 0.000000 )
>
> a(3) = ( 0.000000 0.000000 2.665261 )
>
> 0%
>
> bravais-lattice index = 0
>
> lattice parameter (alat) = 11.6370 a.u.
>
> unit-cell volume = 4491.4283 (a.u.)^3
>
> crystal axes: (cart. coord. in units of alat)
>
> a(1) = ( 1.000000 0.000000 0.000000 )
>
> a(2) = ( -0.471829 1.069357 0.000000 )
>
> a(3) = ( 0.000000 0.000000 2.665261 )
>
> 1%
>
> bravais-lattice index = 0
>
> lattice parameter (alat) = 11.7534 a.u.
>
> unit-cell volume = 4627.5231 (a.u.)^3
>
> crystal axes: (cart. coord. in units of alat)
>
> a(1) = ( 1.000000 0.000000 0.000000 )
>
> a(2) = ( -0.471829 1.069357 0.000000 )
>
> a(3) = ( 0.000000 0.000000 2.665261 )
>
> Once again, thank you very much for giving time to my query.
> I hope for consistent help in future also.
>
> Best Wishes,
>
> Ms. Rekha
>
> On Sat, Apr 4, 2020 at 5:43 PM Rita Maji <rita.maji at niser.ac.in> wrote:
>
>> Hi,
>> Both way it should work, as you mentioned above. You can check the volume
>> in your output files.
>>
>> Thanks,
>> Rita
>>
>> Rita Maji
>> Research scholar
>> School of Physical Sciences
>> National Institute of Science Education and Research
>> Bhubaneswar, 752050
>> Odisha, India
>>
>>
>> On Fri, Apr 3, 2020 at 4:38 PM rekha sharma <rekha1997jpr at gmail.com>
>> wrote:
>>
>>> Dear All,
>>>
>>> Hope you are healthy during this hard time of COVID-19.
>>>
>>> I want to do some scf calculations at a slightly larger volume and
>>> smaller volume than the equilibrium volume  to compute gruneisen parameter.
>>> I tried with two different approaches to calculate the volume and  for
>>> both the cases my celldm's are different.
>>> I am seeking your expert guidance to choose the approach which is
>>> correct one.
>>>
>>> My system is with ibrav=-12 where the QE.in file adopts below geometry.
>>> ...
>>> &SYSTEM
>>>   ecutrho =   560
>>>   ecutwfc =   70
>>>   ibrav = 0
>>>   nat = 20
>>>   ntyp = 3
>>> /
>>> ...
>>> CELL_PARAMETERS angstrom
>>>    6.962369043   0.000000000  -0.001331115 (This 0.001331115 is deviated
>>> after vc-relax)
>>>    0.000000000   7.866710453   0.000000000
>>>   -6.770669758   0.000000000   9.932067578
>>>
>>>
>>> In one of the approach I used celldm(1)=  1.870829, 1.88973, 1.908623
>>> [converted values of 0.99, 1, 1.01 in Bohr] for minus, orig and plus volume
>>> deviation whereas I kept  my cell parameters as such as above
>>>
>>> In this case the celldm's are
>>>                        Minus                     original
>>>  Plus
>>> celldm(1)=   18.5821709383,   18.7699067564,    18.9575631139
>>> celldm(2)=    0.7920102607,     0.7920102607,     0.7920102607
>>> celldm(3)=    0.7009623470,     0.7009623470,     0.7009623470
>>> celldm(5)=    0.0191088849,     0.0191088849,    0.0191088849
>>> In this case celldm's 2,3,5 are same.
>>>
>>> while in other case I changes Crystal lattice vectors V1 only by +/-1%
>>> without defining celldm under &SYSTEM
>>> In this case my celldm's are
>>>                       minus 1%              Orig
>>>  Plus 1%
>>> celldm(1)=   18.7677900578,  18.7698683460,   18.7728685334
>>> celldm(2)=    0.7920979656,    0.7920102607,     0.7918836856
>>> celldm(3)=    0.6940295700,     0.7009623470,    0.7078588256
>>> celldm(5)=    0.0120986705,    0.0191088849,     0.0261162263
>>> here celldm's 2,3,5 are different and celldm(1) is different than I have
>>> in the case 1st.
>>>
>>> Can you please guide me how to set my volume at slightly larger volume
>>> and smaller volume than the equilibrium volume ?
>>> Your help will be very helpful for me and I will be grateful to you all.
>>>
>>> Thank you very much in advance.
>>>
>>> Best wishes
>>>
>>> Ms. Rekha
>>> Teaching Assistant,
>>> Department of Physics
>>> RK college, Jaipur, India
>>> _______________________________________________
>>> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso
>>> )
>>> users mailing list users at lists.quantum-espresso.org
>>> https://lists.quantum-espresso.org/mailman/listinfo/users
>>
>> _______________________________________________
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>
>
>
> --
>
>
>
>
> Best wishes
>
> Ms. Rekha
> Teaching Assistant,
> Department of Physics
> RK college, Jaipur, India
> Mob.: +11 90-95 790 71 697
> Email: rekha1997jpr at gmail.com
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu/quantum-espresso)
> users mailing list users at lists.quantum-espresso.org
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