ABINIT Discussion Forums

Dear all Greetings... I am trying to calculate band gap of cubic perovskite RbGeCl3, attached is my inputs and outputs. The value of the band gap changes with the change of the number of bands used in the computation of Eigen functions and Eigen values (dataset 2), How I know what the correct number...

Dear Eric

check that
Thanks for your help always

Best regards

Nawzad

Dear Eric
When i was varying lattice parameters of the non-cubic phase, i was varying in somehow to keep a/c ratio constant..
I have tried optimization at hydrostatic pressures also, The non-cubic phase was turning to almost the cubic one, means it gives me nearly the same results...

Regards

Nawzad

Dear all I am trying to calculate phase transition of CsSnBr3 from pm-3m cubic to p4/mbm tetragonal under pressure the cubic contains 5 atoms per unit cell while tetragonal contains 10 atoms per unit cell I have varied lattice parameters of the unit cell of both and calculated energy then I have cal...

Dear Eric
I was following a specific reference for what is related to the Wyckoff position, Unfortunately the reference was not quit correct. I feel sorry for bothering you...My input file is working correctly now
Thanks a lot

Nawzad

I have found the correct wyckoff positions and the output file tells me the space group is correct,, everything work well except the c/a ratio becomes 1 while it suppose to keep the structure tetragonal (c/a=constant),, how to keep c/a ratio constant in abinit please? Excellent, great! For the c/a,...

Dear Eric I have found the correct wyckoff positions and the output file tells me the space group is correct,, everything work well except the c/a ratio becomes 1 while it suppose to keep the structure tetragonal (c/a=constant),, how to keep c/a ratio constant in abinit please? Best regards Nawzad

Dear Nawzad, The positions you sent are not for doubled cell, right? Best wishes, Eric Dear Eric I have tried to get fractional coordinates using software SPUDS, following are the resultant coordinates: Cs 4b 0.0 0.5 0.25 Pb 4c 0.0 0.0 0.0 Cl 4a 0.0 0.0 0.25 Cl 8h 0.3428 0.8428 0.0 How to translate...

ebousquet wrote: ↑

Mon Mar 30, 2020 9:44 am

Dear Nawzad,
The positions you sent are not for doubled cell, right?
Best wishes,
Eric

Dear Eric
No, it is for one unit cell, a=b not equal to c

Regards

Nawzad

Dear Nawzad, You need to extend the cell and break the symmetry by moving the atoms accordingly, is it what you did? Best wishes, Eric Dear Eric I have already these following extensions for perovskite 0.0 0.0 0.0 0.5 0.5 0.51 0.5 0.5 0.0 0.5 0.0 0.5 0.0 0.5 0.5 and 0.0 0.0 0.0 0.5 0.5 0.51 0.5 0.5...

Dear Eric
I have already tried extensions but still no relaxation happens...
Thanks a lot

Nawzad

Dear Nawzad, You indeed break the symmetries with the cell parameters but you kept the atomic positions to high-symmetry ones and it sounds your system goes back to cubic if all the atomic positions are in high-sym (and I would say as it should be for perovskites without epitaxial constraints). Alt...

The code stops at the level of the parser hence it does not enter the SCF cycle. As mentioned in the error message: Found the token NPSPALCH in the input file. This name is not one of the registered input variable names (see https://www.abinit.org/doc). NPSPALCH is an internal variable (the name st...

Dear Nawzad, To me it is not possible that the program runs a few relaxation steps without complaining about the input file and stops about a wrong input variable after passing the initial input variables test... Could you send your output file and eventually the log file? Thanks, Eric Dear Eric Yo...

Dear all Greetings I am trying to do optimization for tetragonal phase of a perovskite specifically CsPbCl3 I give spgroup input variable which 140 due to papers but my run stops and gives me the following error: --- !ERROR src_file: symatm.F90 src_line: 201 mpi_rank: 13 message: | Largest error (ab...

Dear Eric Thanks for the reply the error message is the following --- !ERROR src_file: chkvars.F90 src_line: 403 mpi_rank: 13 message: | Found the token NPSPALCH in the input file. This name is not one of the registered input variable names (see https://www.abinit.org/doc). Action: check your input ...

Dear Jmb
Thanks for the reply
I have checked the right version inputs and it is same but still the computer stops after a couple times of optimization
Regards

Nawzad

Dear all I want to study the effect to doping Sn into CsPbCl3, here is my input # DATASET configuration ndtset 1 # Atomic Structure #----------------- acell 5 5 5 Angstr natom 5 ntypat 3 typat 1 2 2 2 3 rprim 1 0 0 0 1 0 0 0 1 xred 0.0 0.0 0.0 0.5 0.0 0.5 0.0 0.5 0.5 0.5 0.5 0.0 0.5 0.5 0.5 prtcif 1...

ebousquet wrote:Dear Nawzad,
I would say the most general directions to break all the symmetries.
Best wishes,
Eric

Thanks Eric
I will try that

Nawzad

Dear Nawzad ABINIT performs the structural optimizations by keeping the symmetries of the initial structure. It seems that your system has the cubic symmetry (Pm-3m). If you do not allow ABINIT to leave this space group, it is normal that the system remains always cubic. Simply break the symmetries...

Dear Nawzad, Thanks so much for your reply. What I meant was something similar to having optcell=2. However, optcell=2 allows for full relaxation subject to symmetry imposed in the initial guess structure. Here I do not know the symmetry groups of the materials of interest and wish to find those ou...

Dear cgs12
see input variables opcell and ionmove ...
best wishes

Nawzad

Dear Nawzad, calculate total energy as a function of pressure for both cubic and orthorhombic structures. there will be crossover at some pressure (you said experimental one is 0.4GPa). You have to use the bandgaps corrosponding to minimum energy structure at each pressure. regards -rajaraman Dear ...

Hello
I know this post is not new, but have you guys solved the problem? because I have the same problem with tetragonal perovskite structure. it is turning to cubic
any help plz?

Nawzad

Hi everybody I am trying to optimize the tetragonal phase under 5 GPa pressure, but the relaxed atomic coordinates and optimized unit cell dimensions turns to cubic phase (c/a=1), while it should stay a tetragonal the following is my input file #Datasets: convergence on ecut #ndtset 16 #Cell and ato...