[Pw_forum] Inconsistencies in the CELL_PARAMETERS - ibrav=5

[Marino Vetuschi Zuccolini]

Hello to all,

I would like to propose to your attention an apparent inconsistency in the matrix of the CELL_PARAMETERS section that I noticed during a relaxation of a crystal with trigonal symmetry (ibrav=5, in attach).
These inconsistency arise writing few lines in output_tau.f90 to enable the code to print the crystal parameters celldm() for each optimization step.

This is the output of these few lines of code with a simple explanation

...
New celldm() values

1)  celldm(1) =  10.118244326   5.354344288	# new cell edge in bohr and angstrom
2)  celldm(4) =   0.647279099			# cos(alpha) solved respect to c in tx
3)  |tx|      =   0.419952914   0.419952914	# value of tx as reported in INPUT.PW and in the code
						  compared with the element of the matrix at(1,1)
4)  |ty|      =   0.242459928   0.242459928	# value of tx as reported in INPUT.PW and in the code
						  compared with the element of the matrix at(2,1)
5)  |tz|      =   0.874558593  >0.911266395<	# value of tx as reported in INPUT.PW and in the code
						  compared with the element of the matrix at(3,1)
6)   c_tx     =   0.647279099			# cos(alpha) solved respect to c in tx - redundant with 2)
7)   c_ty     =   0.647279099			# cos(alpha) solved respect to c in ty
8)   c_tz     =  >0.745609664<			# cos(alpha) solved respect to c in tz
...

Points 5) and 8) seem to be not consistent as expected at least by me :)

Please, can someone explain where probably I'm going wrong?

Many thanks to all

m.

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*******************************************************
Marino Vetuschi Zuccolini
zucco at dipteris.unige.it
Researcher / Geochemist
Laboratory of Geochemistry

DIPartimento per lo studio della TErra e delle sue RISorse - Universit?  di Genova
Tel. ++39 010 3538136 Fax. ++39 010 352169
Corso Europa 26, 16132 - Genova - Italy