Maybe the question was about the definition of such matrix (since it is not symmetric, it is a legitimate question). The three rows are the cartesian coordinates of the three primitive vectors of the lattice. The following piece of code I wrote some time ago should convert from lattice vectors to crystalographic parameters (no warranty)
Paolo subroutine cell2abc ( alat, at, a,b,c,cosab,cosac,cosbc ) ! ! returns crystallographic parameters a,b,c from lattice vectors ! USE kind, ONLY: dp USE constants, ONLY: bohr_radius_angs IMPLICIT NONE ! REAL(DP), INTENT (IN) :: alat, at(3,3) REAL(DP), INTENT (OUT) :: a,b,c, cosab, cosac, cosbc REAL(DP) :: norm1, norm2, norm3 ! ! norm1 = SQRT ( at(1,1)**2 + at(2,1)**2 + at(3,1)**2 ) norm2 = SQRT ( at(1,2)**2 + at(2,2)**2 + at(3,2)**2 ) norm3 = SQRT ( at(1,3)**2 + at(2,3)**2 + at(3,3)**2 ) ! a = alat * norm1 / bohr_radius_angs b = alat * norm2 / bohr_radius_angs c = alat * norm3 / bohr_radius_angs ! cosab = (at(1,1)*at(1,2) + at(2,1)*at(2,2) + at(3,1)*at(3,2))/norm1/norm2 cosac = (at(1,1)*at(1,3) + at(2,1)*at(2,3) + at(3,1)*at(3,3))/norm1/norm3 cosbc = (at(1,3)*at(1,2) + at(2,3)*at(2,2) + at(3,3)*at(3,2))/norm3/norm2 ! END SUBROUTINE cell2abc Paolo On Wed, May 6, 2015 at 2:25 PM, Giuseppe Mattioli < [email protected]> wrote: > > Dear Francesco > > > CELL_PARAMETERS (alat= 9.37304158) > > *_0.998026269_* 0.000004734 -0.013893833 > > 0.000009261 _*1.956757114*_ -0.000006827 > > -0.117999199 -0.000006751 *_1.878825464_* > > This is a matrix containing the projections of the optimized lattice > parameters on the cartesian axes in alat units (alat=9.37304158 bohr). If > you > want your alpha-beta-gamma angles you can calculate them. If you are lazy > (I usually am with nonorthogonal cells...) you may open the pw.x output with > xcrysden and figure out the values with the angle-measurement tool. > > HTH > Giuseppe > > On Wednesday, May 06, 2015 12:41:09 PM Francesco Pelizza wrote: > > Hi to everyone, > > > > I am sorry to bother for such a simple question, but I need to be sure > > about what QE is giving me in the OUTPUT file. > > > > After a VC-relaxation on a cell with angles with one or more of alpha > > beta gamma angles different from 90°, the VC-relaxation OUTPUT file > > gives out this: > > > > CELL_PARAMETERS (alat= 9.37304158) > > *_0.998026269_* 0.000004734 -0.013893833 > > 0.000009261 _*1.956757114*_ -0.000006827 > > -0.117999199 -0.000006751 *_1.878825464_* > > > > The Bold and underlined values are the new Alat, Blat and Clat factor to > > multiplicate the old alat given, to have the new cell dimension in bohrs. > > > > But I guess the other numbers are giving me the alpha beta and gamma > > angles (celldm 4-5-6).... > > > > But who is who? > > > > Thank you very much for reading! > > > > Francesco Pelizza > > ******************************************************** > - Article premier - Les hommes naissent et demeurent > libres et ègaux en droits. Les distinctions sociales > ne peuvent être fondèes que sur l'utilitè commune > - Article 2 - Le but de toute association politique > est la conservation des droits naturels et > imprescriptibles de l'homme. Ces droits sont la libertè, > la propriètè, la sùretè et la rèsistance à l'oppression. > ******************************************************** > > Giuseppe Mattioli > CNR - ISTITUTO DI STRUTTURA DELLA MATERIA > v. Salaria Km 29,300 - C.P. 10 > I 00015 - Monterotondo Stazione (RM), Italy > Tel + 39 06 90672836 - Fax +39 06 90672316 > E-mail: <[email protected]> > http://www.ism.cnr.it/english/staff/mattiolig > ResearcherID: F-6308-2012 > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum >
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