Hi, QE users.Recently I plan to perform free energy calculations of CO
absorption using ph.x, matdyn.x, q2r.x and fqha.x. However, I meet mainly 2
problems.1. When I do phonon calculation of isolated CO molecule with q points
sampling automatically 2x2x2, I find large negative frequency emerges in DOS.
Could anyone tell me why ph.x yields negative frequency? Moreover if I want to
eliminate the negative frequency, should I decrease the tr2_ph value?2. When I
do phonon calculation of the CO absorbed slab, to simplify the calculation, I
set start_irr and last_irr parameters including three translational degrees of
freedom of C and O atom. However, after each q point iteration, ph.x outputs
one line like:Not Davison diagonalization, representation 0 is not done.As a
result, no frequency information is yielded, although ph.x job terminates
normally. However, it is hard to understand representation 0, because
irreducible representation in ph.x is marked from 1, not 0. I don't know how I
can solve this problem.Any suggestions will be appreciated. Best regards.Yike
HuangPhD candidate.Dalian Institute of chemistry and physics, CAS, China.
-------- 原始信息 --------发件人： Luiz Gustavo Davanse da Silveira
<[email protected]> 日期: 2020/2/19 21:03 (GMT+08:00) 收件人：
[email protected] 主题： [QE-users] Advices on ralaxing perovskite
supercells Greetings,I am using QE 6.4.1 to relax the atomic positions of a
BiFeO3 40 atomsupercell, but the calculation didn't converge after 100 scf
steps (thefinal scf accuracy was about 5E-4). I am a new QE user and I really
don'tknow what to change in order to the calculation successfully run.
Anyadvice is very much appreciated.My input follows bellow:&control
calculation = 'relax' prefix = 'bfo' pseudo_dir = './sssp' outdir =
'./outdir' etot_conv_thr = 1.0e-5 forc_conv_thr = 1.0e-4/&system ibrav =
0 nat = 40, ntyp = 3, ecutwfc = 120, ecutrho = 960 lda_plus_u =
.TRUE., Hubbard_U(2) = 4/&electrons conv_thr = 1e-6/&ions ion_dynamics
= 'bfgs'/ATOMIC_SPECIES Bi 208.98 Bi_pbe_v1.uspp.F.UPF Fe 55.85
Fe.pbe-spn-kjpaw_psl.0.2.1.UPF O 16 O.pbe-n-kjpaw_psl.0.1.UPFATOMIC_POSITIONS
(crystal) Bi 0.000000000000000 0.000000000000000 0.000000000000000 Bi
0.500000000000000 0.000000000000000 0.000000000000000 Bi
0.000000000000000 0.500000000000000 0.000000000000000 Bi
0.500000000000000 0.500000000000000 0.000000000000000 Bi
0.000000000000000 0.000000000000000 0.500000000000000 Bi
0.500000000000000 0.000000000000000 0.500000000000000 Bi
0.000000000000000 0.500000000000000 0.500000000000000 Bi
0.500000000000000 0.500000000000000 0.500000000000000 Fe
0.250000000000000 0.250000000000000 0.250000000000000 Fe
0.750000000000000 0.250000000000000 0.250000000000000 Fe
0.250000000000000 0.750000000000000 0.250000000000000 Fe
0.750000000000000 0.750000000000000 0.250000000000000 Fe
0.250000000000000 0.250000000000000 0.750000000000000 Fe
0.750000000000000 0.250000000000000 0.750000000000000 Fe
0.250000000000000 0.750000000000000 0.750000000000000 Fe
0.750000000000000 0.750000000000000 0.750000000000000 O
0.187667999289205 0.312332000710795 0.000000000000000 O
0.812332000710795 0.187667999289205 0.000000000000000 O
0.312332000710795 0.687667999289205 0.000000000000000 O
0.687667999289205 0.812332000710795 0.000000000000000 O
0.312332000710795 0.187667999289205 0.500000000000000 O
0.687667999289205 0.312332000710795 0.500000000000000 O
0.187667999289205 0.812332000710795 0.500000000000000 O
0.812332000710795 0.687667999289205 0.500000000000000 O
0.000000000000000 0.187667999289205 0.312332000710795 O
0.500000000000000 0.312332000710795 0.187667999289205 O
0.000000000000000 0.812332000710795 0.187667999289205 O
0.500000000000000 0.687667999289205 0.312332000710795 O
0.000000000000000 0.312332000710795 0.687667999289205 O
0.500000000000000 0.187667999289205 0.812332000710795 O
0.000000000000000 0.687667999289205 0.812332000710795 O
0.500000000000000 0.812332000710795 0.687667999289205 O
0.312332000710795 0.000000000000000 0.187667999289205 O
0.687667999289205 0.000000000000000 0.312332000710795 O
0.187667999289205 0.500000000000000 0.312332000710795 O
0.812332000710795 0.500000000000000 0.187667999289205 O
0.187667999289205 0.000000000000000 0.812332000710795 O
0.812332000710795 0.000000000000000 0.687667999289205 O
0.312332000710795 0.500000000000000 0.687667999289205 O
0.687667999289205 0.500000000000000 0.812332000710795K_POINTS
(automatic) 4 4 4 0 0 0CELL_PARAMETERS (angstrom) 7.8 0.0 0.0 0.0 7.8 0.0 0.0
0.0 7.8Best regards,Luiz G. D. SilveiraUniversidade Federal do Paraná -
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