[QE-users] Relaxation on LaTe3
Alejandro Lasso Castillo
alejandro.lasso-castillo at universite-paris-saclay.fr
Fri Jul 12 12:06:30 CEST 2024
Dear Prof. Giannozzi,
Thank you for your response. I apologize for my late reply.
I succeeded with the relaxation of my crystal structure achieving the following forces ans stress tensor.
Forces acting on atoms (cartesian axes, Ry/au):
atom 1 type 1 force = 0.00000000 0.00000000 0.00001488
atom 2 type 1 force = 0.00000000 0.00000000 -0.00001488
atom 3 type 2 force = 0.00000000 0.00000000 0.00000844
atom 4 type 2 force = 0.00000000 0.00000000 -0.00000844
atom 5 type 2 force = 0.00000000 0.00000000 -0.00001271
atom 6 type 2 force = 0.00000000 0.00000000 0.00001271
atom 7 type 2 force = 0.00000000 0.00000000 -0.00001894
atom 8 type 2 force = 0.00000000 0.00000000 0.00001894
Total force = 0.000040 Total SCF correction = 0.000000
Computing stress (Cartesian axis) and pressure
total stress (Ry/bohr**3) (kbar) P= -0.07
-0.00000070 0.00000000 -0.00000000 -0.10 0.00 -0.00
0.00000000 -0.00000036 -0.00000000 0.00 -0.05 -0.00
-0.00000000 0.00000000 -0.00000034 -0.00 0.00 -0.05
However, when performing the phonons calculations at the Gamma point I obtained all negative frequencies:
freq ( 1) = -93.901745 [THz] = -3132.225047 [cm-1]
freq ( 2) = -88.011019 [THz] = -2935.731590 [cm-1]
freq ( 3) = -76.385627 [THz] = -2547.950243 [cm-1]
freq ( 4) = -76.150629 [THz] = -2540.111574 [cm-1]
freq ( 5) = -70.602435 [THz] = -2355.043727 [cm-1]
freq ( 6) = -70.549858 [THz] = -2353.289943 [cm-1]
freq ( 7) = -67.081504 [THz] = -2237.598108 [cm-1]
freq ( 8) = -66.962776 [THz] = -2233.637768 [cm-1]
freq ( 9) = -65.079559 [THz] = -2170.820413 [cm-1]
freq ( 10) = -64.752061 [THz] = -2159.896266 [cm-1]
freq ( 11) = -47.521629 [THz] = -1585.150933 [cm-1]
freq ( 12) = -47.342909 [THz] = -1579.189469 [cm-1]
freq ( 13) = -46.459335 [THz] = -1549.716620 [cm-1]
freq ( 14) = -46.436561 [THz] = -1548.956937 [cm-1]
freq ( 15) = -44.002439 [THz] = -1467.763369 [cm-1]
freq ( 16) = -43.980006 [THz] = -1467.015088 [cm-1]
freq ( 17) = -42.040378 [THz] = -1402.316054 [cm-1]
freq ( 18) = -42.036814 [THz] = -1402.197176 [cm-1]
freq ( 19) = -27.016208 [THz] = -901.163687 [cm-1]
freq ( 20) = -27.002908 [THz] = -900.720056 [cm-1]
freq ( 21) = -15.609053 [THz] = -520.661973 [cm-1]
freq ( 22) = -15.040852 [THz] = -501.708804 [cm-1]
freq ( 23) = -14.265259 [THz] = -475.837822 [cm-1]
freq ( 24) = -14.243345 [THz] = -475.106863 [cm-1]
I checked the F.A.Q. page from Quantum Espresso but the frequencies are not small, thus I guess imposing ASR is not sufficient to figure out this problem.
I attach my scf file including the relaxed structure, I kindly ask you (or anyone in the community), to give some advice on what to do.
Thank you very much in advance. Best regards,
Alejandro Lasso Castillo
Erasmus Mundus Joint Master Student
Quantum Science and Technologies (QUARMEN)
-----Mensaje original-----
De: Paolo <paolo.giannozzi at uniud.it>
Para: Quantum <users at lists.quantum-espresso.org>
CC: Alejandro <alejandro.lasso-castillo at universite-paris-saclay.fr>
Fecha: miércoles, 12 de junio de 2024 18:28 CEST
Asunto: Re: [QE-users] Relaxation on LaTe3
There might be a small mismatch, due to numerical reasons, between
forces and energies, in which case the BFGS minimization will never
reach the zero-force configuration. You may try to use damped dynamics
instead. BFGS uses both forces and energies, damped dynamics only forces.
In order to have very precise force values, one needs a highly converged
scf, but the scf threshold you have used (conv_thr) is very small so I
don't think this is the origin of the problem
Paolo
On 12/06/2024 16:59, Alejandro Lasso Castillo via users wrote:
> Dear users,
>
> I am currently trying to perform phonon calculations on LaTe3, and one
> keypoint in order to have good results is a very well relaxed structure.
> For this purpose I use a force threshold of 1d-05 (see input file attached).
>
> However, I find that it is very difficult to achieve this threshold (and
> it becomes harder when increasing the density of k-points). For a k-grid
> of 12 x 2 x 12 I try to relax the structure and eventually the bfgs
> algorithm gets stuck
> into the same three configurations. My strategy so far has been to
> reintroduce the best structure from the output into the input file and
> relaunch it but I can not achieve forces less than 6d-05.
>
> I ask you for some advice in order to achieve my threshold in case you
> have some experience with this kind of materials.
>
> *Alejandro Lasso Castillo*
> /Erasmus Mundus Joint Master Student/
> /Quantum Science and Technologies (QUARMEN)/
>
>
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--
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 206, 33100 Udine Italy, +39-0432-558216
X SCUOLA ENERGIE RINNOVABILI 16-21/9/2024 - PRE-ISCRIZIONE
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