# [Pw_forum] [pw-forum]: Celldm(4) Celldm(5) Celldm(6)

stefano de gironcoli degironc at sissa.it
Fri Nov 20 12:49:47 CET 2015

```On 20/11/2015 12:41, Francesco Pelizza wrote:
> Thank you very much !!
>
> so cos (bc) cos(ac) cos(ab)
>
> a b c are in radians, degrees or something else
something else of course but I'm sure that if you try hard to think what
you would have done if you had tried to solve the problem yourself

stefano
>
>
> On 20/11/15 10:40, Giovanni Cantele wrote:
>> You can use the CELL_PARAMETERS card with ibrav=0 (so no need to compute the angles) or directly use the
>> definition of celldm(4), celldm(5), celldm(6) with ibrav=14 from Doc/INPUT_PW.txt:
>>
>> celldm(4)= cos(bc)
>>
>> b —> -0.004621093   2.150980697   0.080635052
>> c —> -0.031624028   0.077886584   1.892891072
>> celldm(4) = 0.0785376
>>
>> celldm(5)= cos(ac)=0.0165872
>>
>> celldm(6)=cos(ab)=-0.00341855
>>
>> Giovanni
>>
>>
>>
>>> On 20 Nov 2015, at 11:19, Francesco Pelizza <francesco.pelizza at strath.ac.uk> wrote:
>>>
>>> Hi dear Users and Developers,
>>>
>>> I really need a full explanation on how to get Celldm(4) Celldm(5)
>>> Celldm(6) from a VC-relaxation.
>>>
>>> The optimized structure of a system with angles between a-lat b-lat a
>>> c-lat not equals to 90° is given to me in some systems I am studying,
>>>
>>> But I can not find a way of putting this in a new input file.
>>>
>>> If I masure with xcrysden the inclination between periodic images, I got
>>> an angle that if i translate in the cosine value and put it into the
>>> input file, it does not give me the right angle when I open again the
>>> input file with xcrysden.
>>> Also a SCF calculation does not give a value identical or not even
>>> slightly different from the VC-rel calculation itself.
>>>
>>> So, How can I find out exactly Celldm(4) Celldm(5) Celldm(6) from this
>>> piece of output file?
>>>
>>> How do I put this in an input file being sure that quantum espresso will
>>> consider this value for building the lattice and doing the calculation
>>> properly ??
>>>
>>> Thank you very much for your time and patience
>>>
>>> Francesco Pelizza - PhD
>>> Strathclyde University (Glasgow)
>>>
>>> HERE you can find an output file as example
>>>
>>>
>>> Begin final coordinates
>>>        new unit-cell volume =   3435.21521 a.u.^3 (   509.04637 Ang^3 )
>>>
>>> CELL_PARAMETERS (alat=  9.35454172)
>>>      1.031703302  -0.002607611   0.034483284
>>>     -0.004621093   2.150980697   0.080635052
>>>     -0.031624028   0.077886584   1.892891072
>>>
>>> ATOMIC_POSITIONS (angstrom)
>>> H        2.323443642   3.458500775   8.048639166
>>> H        2.246157109   6.259499847   5.493082766
>>> H        2.238584163   4.257844190   0.859706518
>>> H        3.682576551   4.461248011   7.513953456
>>> H        3.660946840   5.289309420   5.076217107
>>> H        2.349858362   7.288089944   3.177035899
>>> H        3.698019711   6.240499825   2.728594264
>>> H        3.699705365   5.164845115   0.461710112
>>> F        2.578959296   7.555136884   0.769673740
>>> F        0.723629375   6.423372715   1.255939854
>>> F        2.384732674   3.966152941   3.106747236
>>> F        0.653462109   5.273905894   3.651911386
>>> F        2.644696706   2.964473519   5.656123191
>>> F        0.735387849   4.041727492   6.056045010
>>> F        0.629819356   5.581707632   8.226678603
>>> F        2.449175259   6.758487891   7.688004312
>>> F        4.791542403   2.350295723   2.918699000
>>> F        5.145230100   1.372558160   5.464114891
>>> H        3.794899005   0.874565766   1.033564982
>>> H        3.767987315   0.169480940   8.124815255
>>> F        1.620809549   1.343881537   2.353960638
>>> H        0.055376396   1.880995718   0.351068538
>>> F        1.746935882   0.059135078   4.717276882
>>> H        0.118749183   1.089942064   7.543474278
>>> H        0.038360119   8.721213695   5.604899727
>>> H        0.156416543   9.733931543   3.301761239
>>> F        1.606381831   9.555176644   7.542110410
>>> F        1.724803088  10.423382736   0.580085061
>>> H        3.762597275   9.742742557   6.180086748
>>> H        3.818806059  10.647160213   3.895291475
>>> F        4.834332727   8.431554403   8.190079715
>>> F        5.022683471   9.219462377   1.286641665
>>> C        4.861902815   0.149655116   8.161361938
>>> C        4.884761682   0.947642455   1.045408665
>>> C        0.337188869   0.143176054   4.742567438
>>> C        0.232687916   1.146022481   2.332101032
>>> C        2.593624135   4.380706568   7.522390456
>>> C        2.129082034   4.198114186   6.068998645
>>> C        2.035262317   5.577048626   8.307268734
>>> C        2.567916441   5.297168460   5.092510941
>>> C        2.062790705   5.205690370   3.651450062
>>> C        2.607997073   5.181809062   0.410338732
>>> C        2.124256003   6.343778231   1.286849130
>>> C        2.609613700   6.314467444   2.746950137
>>> C        0.204140831   9.649137133   7.505914552
>>> C        0.317897336  10.413912382   0.493174549
>>> C        4.910634377  10.672243764   3.875929892
>>> C        4.854146045   9.672373698   6.207264609
>>> End final coordinates
>>>
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```