ABINIT Discussion Forums

Dear ssh77,
Abinit works with the unit cell and not the asymmetric unit cell (i.e. with only minimal Wyckoff sites) such that you have to list all the atoms of the unit cell and not the asymmetric ones. Well, I guess this is your problem.
Best wishes,
Eric

Dear Nawzad, In your case, I would check the phonon dispersions of the cubic 5 atom cell at different pressure to check whether you have an instability or not. If no instability is present, it will mean that the cubic phase is indeed stable in your calculation. If an instability appears (reported as...

Dear ssh77,
You are running a calculation with 80 atoms on a laptop?? How many CPU and RAM do you have, this is a big calculation that would require a multicore-job to get it running within a decent time...
Best wishes,
Eric

Dear Jerkov, You need to analyze the relaxed cell with a program that will tell you the exact crystal space group in the case of supercell calculation. Abipy or qAgate are directly interfaced with Abinit and can do the job through the spglib python library. You can also use the FINDSYM software from...

Dear Jerkov, OK, you have included the asr, it is not the problem then. If only the points in between the main q-points at which you did the DFPT are giving strange negative results it might means that the q-grid is not large enough to have a good interpolation. You used 2x2x2 q-grid, which night no...

Dear Andrew,
Thank you for your report.
In any case, the user should always check convergence and validity of the pseudo used, even in the case of a often used pseudo, it is possible that it fails in the specific conditions of your system.
Best wishes,
Eric

Hi kittysoman2013,
Did you check other parameters like diemix, diemac before iprcell?
Best wishes,
Eric

Dear Nawzad, If you constrain the cell with acell, then you compute the internal energy at constrained strain and not at hydrostatic pressure. This is important mostly when the system is not cubic since the constrain along a,b and c will not represent the same pressure. I guess this can be your prob...

Dear ssh77,
These extra lines are for internal automatic tests of Abinit, you can disregard them.
Best wishes,
Eric

Dear Suman
Abinit has almost no limit on the number of atoms, 100 is clearly not a problem.
Could it be that your computer does not have enough RAM memory for this calculation?
Best wishes,
Eric

Dear kittysoman2013, Once you add chkprim=0, I'm not sure you can still use the spgroup flag. Your error message is a segmentation fault such that it can be difficult to know its origin (memory allocation problem). Looking at your input I see that you did not initialized all the flags for +U, you ha...

Dear Suman, You should look at the link dbennett1994 gave you (and Stengel reference given there) regarding calculation of Polarization because once you play with hetero-structures, slabs, etc, the proper variable to look at should be D. Additionally, computing P requires to have a zero reference an...

Dear Kevin, I'm not sure if I understand, but you want to compute the polarization through the Berry phase, I guess you did it with berryopt=-1 with Abinit, right? Now, you have to be careful with quantum of polarization problem, see for example: http://palata.fzu.cz/abinitschool/download/We3_polari...

Dear ssh77, I ran your input and everything goes through fine after reading the psp files, so I don't know what can be your problem. Can it be a memory problem (the job takes 6-7 Gb)? Regarding the ixc, if you don't specify a value there, it'll be read directly from the pseudo file and set automatic...

I don't know if Jmol can do it but you can use the new software qAgate which is interfaced with Abinit and can do the job.
To install it, you can do: Best wishes,
Eric

Dear Eliezer, OK, it sounds like you can get easily an error bar of 1% but going lower is CPU time demanding. At this stage you need to know if 1% precision on the WF is enough for you? If so, ecut=16-20 look good. There is something making a noise oscillation but I don't know what can be the origin...

Dear Jerkov, For insulators, the number of bands necessary can be set to the occupied bands only (and with an insulator occopt value). For metals, you have to be sure the number of bands is large enough, but this is a convergence test to do. Is your system metallic? If so, this can be one of the dif...

Dear ssh77,
Did you run the configure by telling it the path of your config file (./configure --with-config-file="CONFIGFILENAME.ac9")?
Best wishes,
Eric

Dear Eliezer,
OK, we can thus see that you don't need such a strict precision on tolvrs to get correct precision on the property you want to compute (WF here) and asking for more would be CPU time waste. Now you can safely test the convergence w.r.t. ecut and kpt.
Best wishes,
Eric

erichmond wrote: ↑

Wed May 20, 2020 6:02 am

What do you mean by "not very optimized".

Might be more SCF or memory demanding...
Eric

Dear Suman, Polarization is not a direct observable and has the problem of lattice quantum, etc. This is the problem you get along x and y (quantum of polarization, not real polarization). You have to get a zero reference structure and see how the polarization evolves with the distortion up to the g...

OK, very good then
Eric

Dear jerkov, The properties are outputed in Cartesian axis. To find the way how to pass from a,b,c to Cartesian and the other way around, you have to use the corresponding transformation matrix. rprim should give you a hint on that, see in the doc https://docs.abinit.org/variables/basic/#rprim . In ...

Dear Eliezer, I completed the tests on iprcel and dielng which are included in an updated version of "PreConditioner parameter evaluation" (attached). Also I put the optimum choices of the preconditioning parameters in a slab run with nstep = 2000. The results were better (iteration 1996-2000 =>4.72...

Dear Eliezer, Thank you for your feedback. Regarding the convergence tests of diemac, diemix, etc it looks like nline and diemac does not change anything and diemix=0.8 is the best value. The SCF is quite smooth without bumps such that this is quite good. For iprcell, I don't have much experience wi...