ABINIT Discussion Forums

Dear colleagues,

I have encountered a problem while trying to analyse the DDB from the RF calc. of N doped rutile TIO2.

First I have calc. pure rutile TiO2 using ngkpt 5 5 10. Everything went nice. PD are good compared to experiments. Then I introduced a 50% doping by changing one O atom with N. I excluded the symmetries from the input. The rest of the file is the same as for the pure TiO2. Abinit version and the cluster are also the same. RF calc. for the doped TiO2 finishes without a problem. But, upon starting anaddb, I get the message

symdm9 : ERROR -
Informations are missing in the DDB.
The dynamical matrix number 9 cannot be built,
since no blok with wavevector -4.000000E-01 2.000000E-01 0.000000E+00
has been found.
Action : add the required block in the DDB, or modify your input file.

Since everything, except the symmetry of the crystal, is the same (for pure TiO2 it's P4_2/m n m (#136); Bravais tP (primitive tetrag.), and for doped TiO2 I get Pm m 2 (# 25); Bravais oP (primitive ortho.)), I presume that this is the reason why this happens. But how can I overcome this error and proceed to obtain the PDs? I'm sending all my files bellow for reference.

Thank you all in advance!

Igor Lukacevic

Hi Igor,

perhaps you did not adapt the qpts for the phonon calculation to the lowered symmetry. This usually means you need more qpts and anaddb can not find the specific one it mentions, which is in the ngqpt grid you gave but not in the DDB file...

To get the q grid irred points, as usual you can run a fictitious gs job with the same cell and the ngkpt equal to the ngqpt you want (shiftk 0 0 0), then read of the irred k.

ciao!

Matthieu

Hi Matthieu,

In the meantime of your response, I figured out the same reason (which is my error). I was just kind of hoping that there is some sinister way in which one could circumvent this issue, using only anaddb options, and not needing to repeat the rf calculations.

Thanks!

Igor

I have an update on this problem.

I have made an additional calc, which gave me the q-points for the cell with lower symmetry (#25). Then, I ran a RF calc, to get the DDBs. But again, when I started the anaddb, I got the same message

symdm9 : ERROR -
Informations are missing in the DDB.
The dynamical matrix number 6 cannot be built,
since no blok with wavevector -3.333333E-01 3.333333E-01 0.000000E+00
has been found.
Action : add the required blok in the DDB, or modify your input file.


How can this be, if I, in the RF calc, used the q-points corresponding to the orthorhombic (#25) cell?

Igor

I apologize sincerely. I missed a minus sign in front of the q-points.

Maybe this subject could be deleted from the forum.

Igor L.