ABINIT Discussion Forums

Dear all, I calculated the phonon frequency and the elph of my system with the input of teph_5.in with abinit, I used 40 Ha ecut and 40 40 40 kpoints and the phonon frequency of the ddb part (tolvr = 1.0 e-18) is positive but when calculating the gkk part (nstep = 1, tolwr = 1.0 d-22), the phonon fr...

Is there any difference betwee the phonon band calculated by trf2_1.in and teph_1.in? I mean , in trf2_1.in , I just got the phonon band structures but in teph_1.in I got both the phonon band structures and the el-ph information because this calculation takes the el-ph interaction into consideration...

Dear all, I am following the example about the el-ph calculation given by abinit. In the example teph_1.in, the calculation was devided into scf part and nscf part for each q point, the example set the nstep=1 for the nscf step. Is that ok to keep this nstep when I do the other calculation? I saw th...

Oh I see, when I first looked at the question I did not read thoroughly I thought you were running a phonon band structure calculation and getting negative frequencies at specific q-points. My mistake, upon 2nd look, I have no real experience doing el-ph calcs Thank you all the same for your answer...

Hello, As a user, I get this problem too. In my experience, you must increase parameters like ngkpt and ecut (try ngkpt first) to help the situation. Sometimes though, if the structure itself is unstable, this negative frequency suggests instabilities in the crystal structure or phase. Increasing n...

Dear all, I am a beginer of abinit and I met some problems while doing the elphon. I did the electron-phonon calculation and when I run the calculation by anaddb , the log file showed that : ================================================================================ Calculation of the interatom...

Dear users/developers, I am doing the test work on abinit as a new user, I calculated the el-ph of the Im-3m BCC H3S with 4*4*4 q points, the results was ok an no negative freq appeared, but as I changed the q points to 8*8*8 and keep other input unchanged. I got a negative freq at one q points abou...

Dear users/developers, I'm a new user of abinit and I am now learning to calculate the el-ph properties by abinit. I finished to calculate the ddb and gkk files by abinit and merged them by mrgddb and mrggkk respectively and then got the Tc value by using the anaddb, but I am really confused by the ...

If you obtained the required pressure at the end of the 1st dataset of your RF calculation, then you are using the correct wavefunction. But since your frequencies are still negative, it means that there is a physical problem in the simulated system taking into account the used approximations (xc, ...

Very much possible. It is known that in some systems phonon frequencies become imaginary at high pressures. You could have the same situation. Try to solve first the problem of different pressures in relaxation and RF calculations. If all you input variables are the same, then you should get the sa...

Very much possible. It is known that in some systems phonon frequencies become imaginary at high pressures. You could have the same situation. Try to solve first the problem of different pressures in relaxation and RF calculations. If all you input variables are the same, then you should get the sa...

That might be the source of your problem. Did you insert the relaxed acell into your RF input file? I see from the inputs your provided in your first post that the acell in the RF input file is the same as in the relaxation input file. If you used that RF input file, you should change acell. Igor Y...

That might be the source of your problem. Did you insert the relaxed acell into your RF input file? I see from the inputs your provided in your first post that the acell in the RF input file is the same as in the relaxation input file. If you used that RF input file, you should change acell. Igor Y...

Hi! 1] Before anything else, you have to make sure that all common variables have the same values in both calculations. And I can see that some of them do not, like ngkpt, etc. Also it is advised to use the same energy tolerance criterion, while you use toldff in the relaxation and tolvrs in RF. Be...

Hi! 1] Before anything else, you have to make sure that all common variables have the same values in both calculations. And I can see that some of them do not, like ngkpt, etc. Also it is advised to use the same energy tolerance criterion, while you use toldff in the relaxation and tolvrs in RF. Be...

Dear users/developers, I'm a new user of abinit and I am now doing the test an exercise, I want to repeat the previous work of H3S bcc cubic structure,the structure should be dynamical stability but when I calculated the phonon after geometry relaxation at 200 GPa , the phonon frequency at q point 0...