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

[Giovanni Cantele]

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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-- 

Giovanni Cantele, PhD
CNR-SPIN
c/o Dipartimento di Fisica
Universita' di Napoli "Federico II"
Complesso Universitario M. S. Angelo - Ed. 6
Via Cintia, I-80126, Napoli, Italy
e-mail: giovanni.cantele at spin.cnr.it
Phone: +39 081 676910
Skype contact: giocan74

ResearcherID: http://www.researcherid.com/rid/A-1951-2009
Web page: http://people.na.infn.it/~cantele