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

Francesco Pelizza francesco.pelizza at strath.ac.uk
Fri Nov 20 12:41:20 CET 2015

```Thank you very much !!

so cos (bc) cos(ac) cos(ab)

a b c are in radians, degrees or something else?

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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```