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ok <br>
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gli chiediamo gli pseudi, per il resto abbiamo tutto. <br>
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sembrerebbe un problema collegato allo scan, alle volte se si usano pseudi PBE i sistemi tendono a esplodere.
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>Da:</b> users <users-bounces@lists.quantum-espresso.org> per conto di Giuseppe Mattioli <giuseppe.mattioli@ism.cnr.it><br>
<b>Inviato:</b> marted¨¬ 14 marzo 2023 12:35<br>
<b>A:</b> users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
<b>Oggetto:</b> Re: [QE-users] unconverged issue in spin-polarized SCAN calculations</font>
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Dear Yi-min Ding<br>
Supposing that the pristine silicon nitride cell converges without <br>
problems, try first to use smearing (uncomment the lines) and to <br>
reduce mixing_beta to a low or very low value (0.1-0.01). I don't know <br>
silicon nitride very well, so excuse me for the possibly stupid <br>
question. Have you tried to use a larger supercell? 33% Al doping <br>
might be not only unphysical, but also the source of wild instability <br>
in scf iterations.<br>
HTH<br>
Giuseppe<br>
<br>
Quoting ¶¡ÒÔÃñ via users <users@lists.quantum-espresso.org>:<br>
<br>
> Dear all,<br>
> I am doing a scf calculation for a FM system using SCAN functional. <br>
> But, the energy in output file is positive, and the run shown no <br>
> converged tendency.<br>
><br>
><br>
> The input and out files are shown below:.<br>
> input:<br>
> &system<br>
> ibrav =4<br>
> a=2.9063917063813576<br>
> c=25<br>
> nat = 7<br>
> ntyp = 3<br>
> ecutwfc = 100.0<br>
> nbnd=48<br>
> nspin=2<br>
> ! starting_magnetization(1)= 0,<br>
> ! starting_magnetization(2)=0,<br>
> ! starting_magnetization(3)=1,<br>
> tot_magnetization =1<br>
> ! occupations='smearing',<br>
> ! smearing='gauss',<br>
> ! degauss=1.0d-2,<br>
> input_dft='scan'<br>
> /<br>
> &electrons<br>
> electron_maxstep = 100<br>
> conv_thr = 1.0d-8<br>
> mixing_mode = 'plain'<br>
> mixing_beta = 0.7<br>
> mixing_ndim = 8<br>
> diagonalization = 'david'<br>
> diago_david_ndim = 4<br>
> diago_full_acc = .true.<br>
> /<br>
> ATOMIC_SPECIES<br>
> Al 26.98 Al.upf<br>
> Si 28.09 Si.upf<br>
> N 14.01 N.upf<br>
> ATOMIC_POSITIONS (crystal)<br>
> Al 0.6666666666666643 0.3333333333333357 <br>
> 0.5000000000000000 <br>
> Si 0.0000000000000000 0.0000000000000000 0.3860058177698406<br>
> Si 0.3333333429999996 0.6666666870000029 <br>
> 0.6139941822301592 <br>
> N 0.0000000000000000 0.0000000000000000 <br>
> 0.4563348732468989 <br>
> N 0.3333333429999996 0.6666666870000029 <br>
> 0.5436651267531011 <br>
> N 0.3333333429999996 0.6666666870000029 <br>
> 0.3651769401128088 <br>
> N 0.0000000000000000 -0.0000000000000000 0.6348230598871913 <br>
> K_POINTS automatic<br>
> 11 11 1 0 0 0<br>
><br>
> .........................................................................................................<br>
> output:<br>
> ...............<br>
> iteration # 99 ecut= <br>
> 100.00 Ry beta= 0.70<br>
> Davidson diagonalization with overlap<br>
> c_bands: 3 eigenvalues not converged<br>
> c_bands: 5 eigenvalues not converged<br>
> c_bands: 5 eigenvalues not converged<br>
> c_bands: 5 eigenvalues not converged<br>
> c_bands: 5 eigenvalues not converged<br>
> c_bands: 5 eigenvalues not converged<br>
> ethr = 1.00E-02, avg # of iterations = 24.8<br>
><br>
><br>
> negative rho (up,down): 5.052E+00 2.651E+00<br>
><br>
><br>
> total cpu time spent up to now is <br>
> 1964.0 secs<br>
><br>
><br>
> total energy <br>
> = 3309.58902363 Ry<br>
> estimated scf accuracy < <br>
> 304153.85545920 Ry<br>
><br>
><br>
> total magnetization <br>
> = 1.00 Bohr mag/cell<br>
> absolute magnetization = <br>
> 28.84 Bohr mag/cell<br>
><br>
><br>
> iteration #100 ecut= <br>
> 100.00 Ry beta= 0.70<br>
> Davidson diagonalization with overlap<br>
> ethr = 1.00E-02, avg # of iterations = 12.3<br>
><br>
><br>
> negative rho (up,down): 3.516E+00 2.027E+00<br>
><br>
><br>
> total cpu time spent up to now is <br>
> 1974.9 secs<br>
><br>
><br>
> total energy <br>
> = 2760.95716210 Ry<br>
> estimated scf accuracy < <br>
> 488812.03105752 Ry<br>
><br>
><br>
> total magnetization <br>
> = 1.00 Bohr mag/cell<br>
> absolute magnetization = <br>
> 30.68 Bohr mag/cell<br>
><br>
><br>
> End of self-consistent calculation<br>
><br>
><br>
> convergence NOT achieved after 100 iterations: stopping<br>
> Writing meta-gga kinetic term<br>
><br>
> ...............................................................................................................<br>
> Can you give me some help?<br>
> Thanks in advance.<br>
> Dr. Yi-min Ding<br>
<br>
<br>
<br>
GIUSEPPE MATTIOLI<br>
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
Via Salaria Km 29,300 - C.P. 10<br>
I-00015 - Monterotondo Scalo (RM)<br>
Mob (*preferred*) +39 373 7305625<br>
Tel + 39 06 90672342 - Fax +39 06 90672316<br>
E-mail: <giuseppe.mattioli@ism.cnr.it><br>
<br>
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