<div dir="ltr">Try reducing the tr2_ph parameter. 1D-11 is too high. I have had similar problems in the past and it was solved by reducing tr2_ph. I would suggest trying 1D-13 or 1D-14.<div>-Sridhar</div><div>Purdue University</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 19, 2015 at 9:36 PM, 潭影空人心 <span dir="ltr"><<a href="mailto:774729155@qq.com" target="_blank">774729155@qq.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Dear all,<div> <span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap">I used nq1 = 2, nq2 = 2, nq3 = 2 and </span><span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap">nq1 = 4, nq2 = 4, nq3 = 4</span><span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap"> ,respectively, to do a phonon calculation. There is no </span><span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap">imaginary frequency at the calculated Q</span><span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap"> points, but after calculations of Q2R and MATDYN, </span><span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap">imaginary frequencies appear near GAMMA point(not GAMMA point).</span></div><div><span style="font-family:courier,'courier new',monospace;line-height:19.6000003814697px;white-space:pre-wrap"><br></span></div><div><font face="courier, courier new, monospace"><span style="line-height:19.6000003814697px;white-space:pre-wrap">My settings are as follows:</span></font></div><div><font face="courier, courier new, monospace"><span style="line-height:19.6000003814697px;white-space:pre-wrap">1.lattice relaxation under pressure:</span></font></div><div><font face="courier, courier new, monospace"><div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&control </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> calculation = 'vc-relax' </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> restart_mode = 'from_scratch'</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> prefix = 'cras' </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> pseudo_dir = '/data1/tan1/software/espresso-5.1/pseudo/'</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> outdir = './tempdir/' </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> etot_conv_thr = 1.0D-6</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> forc_conv_thr = 1.0D-4</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> tstress = .true.</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> tprnfor = .true. </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">/ </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&system </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> ibrav = 8</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> A = 5.58</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> B = 3.36</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> C = 6.17</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> nat = 8</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> ntyp = 4</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> ecutwfc = 120</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> occupations = 'smearing'</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> smearing = 'methfessel-paxton'</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> degauss = 0.04</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> nspin = 2</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> starting_magnetization(1) = -1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> starting_magnetization(2) = 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> starting_magnetization(3) = 0 </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> starting_magnetization(4) = 0</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">/ </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&electrons </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> electron_maxstep = 100</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> conv_thr = 1.0d-6</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> mixing_beta = 0.7 </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">/ </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&ions </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> ion_dynamics = 'bfgs' </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">/ </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&cell </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> press = 1500</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> cell_dynamics = 'bfgs' </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> press_conv_thr = 0.1 </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> cell_factor = 2.5d0</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">/</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">ATOMIC_SPECIES </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> Cr1 51.9961 Cr.pz-hgh.UPF</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> Cr2 51.9961 Cr.pz-hgh.UPF</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> As1 74.9216 As.pz-hgh.UPF</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> As2 74.9216 As.pz-hgh.UPF</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">ATOMIC_POSITIONS (crystal) </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">Cr1 0.012000 0.250000 0.201000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">Cr2 0.988000 0.750000 0.799000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">Cr2 0.512000 0.250000 0.299000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">Cr1 0.488000 0.750000 0.701000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">As1 0.195000 0.250000 0.582000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">As2 0.805000 0.750000 0.418000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">As2 0.695000 0.250000 0.918000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">As1 0.305000 0.750000 0.082000 1 0 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">K_POINTS {automatic} </span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">6 8 6 0 0 0 </span></div></div><div><br></div><div style="line-height:19.6000003814697px;white-space:pre-wrap"><br></div><div style="line-height:19.6000003814697px;white-space:pre-wrap">2.interior coordination relaxation:</div><div style="line-height:19.6000003814697px;white-space:pre-wrap">All is the same as above, but "<span style="line-height:19.6000003814697px">ecutwfc = 50"</span></div><div style="line-height:19.6000003814697px;white-space:pre-wrap"><span style="line-height:19.6000003814697px">3.</span><span style="line-height:19.6000003814697px">self-consistent iteration for phonon calculation:</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&control
calculation = 'scf'
restart_mode = 'from_scratch'
prefix = 'cras'
pseudo_dir = '/data1/tan1/software/espresso-5.1/pseudo/'
outdir = './tempdir/'
tstress = .true.
tprnfor = .true.
/
&system
ibrav = 0
celldm(1) = 10.54467182
nat = 8
ntyp = 4
ecutwfc = 50
occupations = 'smearing'
smearing = 'methfessel-paxton'
degauss = 0.05
nspin = 2
starting_magnetization(1) = -1
starting_magnetization(2) = 1
starting_magnetization(3) = 0
starting_magnetization(4) = 0
/
&electrons
electron_maxstep = 200
conv_thr = 1.0d-10
mixing_beta = 0.7
/
ATOMIC_SPECIES
Cr1 51.9961 Cr.pz-hgh.UPF
Cr2 51.9961 Cr.pz-hgh.UPF
As1 74.9216 As.pz-hgh.UPF
As2 74.9216 As.pz-hgh.UPF
CELL_PARAMETERS (alat= 10.54467182)
0.9146 0.0000 0.0000
0.0000 0.4765 0.0000
0.0000 0.0000 0.9628
ATOMIC_POSITIONS (crystal)
Cr1 0.0104 0.2500 0.1827
Cr2 0.9896 0.7500 0.8173
Cr2 0.5104 0.2500 0.3173
Cr1 0.4896 0.7500 0.6827
As1 0.1833 0.2500 0.5616
As2 0.8167 0.7500 0.4384
As2 0.6833 0.2500 0.9384
As1 0.3167 0.7500 0.0616
K_POINTS {automatic}
6 8 6 0 0 0
</span></div><div><span style="line-height:19.6000003814697px">4.</span><span style="line-height:19.6000003814697px;white-space:pre-wrap">self-consistent iteration for electron-phonon coupling:</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">All is the same as phonon calculation but k-mesh 12 16 12,and in addition to "la2F = .true.".</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">5.phonon calculation:</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">&inputph
tr2_ph = 1.0d-11
prefix = 'cras'
fildvscf = 'crasdv'
amass(1) = 51.9961
amass(2) = 51.9961
amass(3) = 74.9216
amass(4) = 74.9216
outdir = './tempdir/',
fildyn = 'cras.dyn',
electron_phonon='interpolated'
el_ph_sigma = 0.005,
el_ph_nsigma = 10,
trans = .true.
ldisp = .true.
alpha_mix(1) = 0.5
recover =.true.
nq1 = 2
nq2 = 2
nq3 = 2
/</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">6.q2r:</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"> &input
zasr='crystal', fildyn='cras.dyn', flfrc='cras222.fc',
la2F=.true.
/</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap">7.&input
asr='crystal', amass(1)=51.9961,amass(2)=51.9961,amass(3)=74.9216,amass(4)=74.9216,
flfrc='cras222.fc', flfrq='cras.freq', q_in_band_form=.true.,
la2F=.true.,dos=.false.
/
8
0.000000 0.000000 0.000000 50
0.500000 0.000000 0.000000 50
0.500000 0.785906 0.000000 50
0.000000 0.000000 0.000000 50
0.000000 0.000000 0.456275 50
0.500000 0.000000 0.456275 50
0.500000 0.785906 0.456275 50
0.000000 0.000000 0.456275 1</span></div><div><span style="line-height:19.6000003814697px;white-space:pre-wrap"><br></span></div></font></div><pre style="font-family:courier,'courier new',monospace;margin-top:0px;margin-bottom:0px;line-height:19.6000003814697px">I am eagerly hoping someone can help me.
Thank you.</pre><pre style="font-family:courier,'courier new',monospace;margin-top:0px;margin-bottom:0px;line-height:19.6000003814697px"><br></pre><pre style="font-family:courier,'courier new',monospace;margin-top:0px;margin-bottom:0px;line-height:19.6000003814697px">tanlin</pre><pre style="font-family:courier,'courier new',monospace;margin-top:0px;margin-bottom:0px;line-height:19.6000003814697px">2015.10.20</pre><br>_______________________________________________<br>
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