<div dir="ltr">Dear all,<div><br></div><div style>I have a question of matdyn.x and dynmat.x.</div><div style>I have calculated phonon dispersion of the materials of a one-dimensional system(Silicon nano wire). <br></div><div style>
Then, the problem occurred. <br></div><div style>First, I estimated the frequency of gamma point using dynmat.x.(result is following)</div><div>As for the result, frequencies also including rotation mode was set to 0. </div>
<div style> <br></div><div style>Next, phonon dispersion of gamma point to X point was calculated using matdyn.x (same structure). Much negative frequencies appeared. </div><div style>Especially an amusing point is that negative frequency appeared of gamma point...</div>
<div style>Is it strange!?!?!?!</div><div style>Negative frequency at gamma point did not appear in dynmat.x . </div><div style>But,negative frequency at gamma point appeared in matdyn.x . <br></div><div style><br></div>
<div style>Please help me....<br></div><div style><br></div><div style>------------------</div><div style>Appendix</div><div style><br></div><div style>In PHonon's example directory , </div><div style><br></div><div style>
<div> Note that the calculation is not intended to be a good one,</div><div> but just a test one! Rotation modes have negative frequencies.</div><div> This is a consequence of the supercell approach. Translational</div>
<div> modes have zero frequency because the translational Acoustic Sum </div><div> Rule (ASR) is imposed by construction in the calculation</div><div> (option asr=.true.)</div><div><br></div><div> calculate the IR cross section (input=<a href="http://sih4.dyn.in">sih4.dyn.in</a>, output=sih4.dyn.out).</div>
<div> By applying the appropriate ASR for molecules (option asr='zero-dim')</div><div> the rotational modes are forced to have zero frequency as well.</div><div><br></div><div>-------------------</div><div><div>
phonons of sinw100</div><div> &inputph</div><div> tr2_ph=1.0d-14,</div><div> prefix='100',</div><div> ldisp=.true.,</div><div> nq1=4, nq2=1, nq3=1</div><div> amass(1)=28.08,</div><div> amass(2)=1.00782503207,</div>
<div> epsil = .true.,</div><div> outdir='./',</div><div> fildyn='100.dyn',</div><div> /</div></div><div><br></div><div>-------------------</div><div style>dynmat::input</div><div style><br></div><div style>
&input fildyn='100.dynG', asr='one-dim' , axis=1 /<br></div><div style><br></div><div style>--------------------</div><div style><br></div><div style>matdyn::input<br></div><div style><br></div><div style>
<div>&input</div><div> asr='one-dim', amass(1)=28.08,amass(2)=1.0078</div><div> flfrc='100-411.fc' , flfrq='100.freq411', q_in_band_form=.true.</div><div>/</div><div>2</div><div>0.0 0.0 0.0 30</div>
<div>0.5 0.0 0.0 1</div><div><br></div><div>---------------------</div><div>dynmat::out<br></div><div><br></div><div><div> Program DYNMAT v.5.0.2 starts on 2Jul2013 at 19:42:14 </div><div><br></div><div> This program is part of the open-source Quantum ESPRESSO suite</div>
<div> for quantum simulation of materials; please cite</div><div> "P. Giannozzi et al., J. Phys.:Condens. Matter 21 395502 (2009);</div><div> URL <a href="http://www.quantum-espresso.org">http://www.quantum-espresso.org</a>", </div>
<div> in publications or presentations arising from this work. More details at</div><div> <a href="http://www.quantum-espresso.org/quote.php">http://www.quantum-espresso.org/quote.php</a></div><div><br></div><div>
Parallel version (MPI), running on 1 processors</div><div><br></div><div> Reading Dynamical Matrix from file 110.dyn1</div><div> ...Force constants read</div><div> ...epsilon and Z* read</div><div>asr rotation axis in 1D system= 3</div>
<div> Acoustic Sum Rule: || Z*(ASR) - Z*(orig)|| = 0.353670E-02</div><div> Acoustic Sum Rule: ||dyn(ASR) - dyn(orig)||= 0.331795E-02</div><div> A direction for q was not specified:TO-LO splitting will be absent</div>
<div><br></div><div> Polarizability (A^3 units)</div><div> multiply by 0.909144 for Clausius-Mossotti correction</div><div> 20.583151 0.000195 0.161462</div><div> 0.000194 22.656585 -0.000011</div>
<div> 0.161579 -0.000011 84.467922</div><div><br></div><div> IR activities are in (D/A)^2/amu units</div><div><br></div><div># mode [cm-1] [THz] IR</div><div> 1 0.00 0.0000 0.0000</div>
<div> 2 0.00 0.0000 0.0000</div><div> 3 0.00 0.0000 0.0000</div><div> 4 0.00 0.0000 0.0000</div><div> 5 75.71 2.2699 0.0000</div><div> 6 104.63 3.1368 0.0000</div>
<div> 7 140.61 4.2154 0.0000</div><div> 8 160.44 4.8100 1.9984</div><div> 9 170.20 5.1025 0.0000</div><div> 10 283.75 8.5066 0.1075</div><div> 11 316.01 9.4738 0.0000</div>
<div> 12 347.15 10.4073 0.0072 ....</div><div><br></div></div><div>---------------</div><div><div style>matdyn::output</div><div><br></div><div> &plot nbnd= 63, nks= 31 /</div><div> 0.000000 0.000000 0.000000</div>
<div> -5.7011 -3.1921 -3.1542 -3.0478 82.8607 90.4273</div><div> 92.7694 106.4356 107.0790 118.9001 135.9974 160.8521</div><div> 165.8887 166.7422 229.7942 306.6637 350.5737 350.9385</div></div><div>
<br></div><div>------------</div><div style>scf :input</div><div style><div> &control</div><div> calculation='scf'</div><div> restart_mode='restart',</div><div> prefix='100',</div><div>
pseudo_dir = './',</div><div> outdir='./'</div><div> tprnfor = .true.</div><div> tstress = .true.</div><div> /</div><div> &system</div><div> ibrav=8,</div><div> celldm(1) = 9.633168021 ,</div>
<div> celldm(2) =3.480290431 ,</div><div> celldm(3) =3.480290431 ,</div><div>! celldm(3) = 3.472149983 ,</div><div> nat= 21,</div><div> ntyp= 2,</div><div> ecutwfc =80.0,</div><div> /</div><div> &electrons</div>
<div> diagonalization = 'cg'</div><div> conv_thr = 1.0d-12</div><div> mixing_beta = 0.2</div><div> electron_maxstep = 10000</div><div> /</div><div>ATOMIC_SPECIES</div><div> Si 28.086 Si.pz-vbc.UPF</div>
<div> H 1.00782503207 H.pz-vbc.UPF</div><div>ATOMIC_POSITIONS bohr</div><div>Si 2.382690171 4.187834839 4.187834839</div><div>Si 4.789323462 1.598594247 6.780982341</div><div>Si 7.195976312 4.187862386 9.374088196</div>
<div>Si 4.789323462 6.780982341 1.598594247</div><div>Si 7.195976312 9.374088196 4.187862386</div><div>Si -0.027227025 6.780971845 6.780971845</div><div>Si 2.382685709 9.374110350 9.374110350</div>
<div>Si 4.789318805 11.963353533 6.780967109</div><div>Si 4.789318805 6.780967109 11.963353533</div><div>H 0.571328310 2.642458237 2.642458237</div><div>H 3.058789041 -0.053654953 8.291479535</div>
<div>H 6.519825955 -0.053761794 5.270564949</div><div>H 9.007284822 2.642456259 10.919495629</div><div>H 3.058789041 8.291479535 -0.053654953</div><div>H 6.519825955 5.270564949 -0.053761794</div>
<div>H 9.007284822 10.919495629 2.642456259</div><div>H 0.571308353 10.919478070 10.919478070</div><div>H 6.519816947 13.615714892 8.291383841</div><div>H 3.058781632 13.615593424 5.270464332</div>
<div>H 6.519816947 8.291383841 13.615714892</div><div>H 3.058781632 5.270464332 13.615593424</div><div>K_POINTS AUTOMATIC</div><div>16 1 1 0 0 0</div><div><br></div><div>---------------</div><div style>
scf:output</div><div style><br></div><div style> Total force = 0.000172 Total SCF correction = 0.000000<br></div><div style><div> total stress (Ry/bohr**3) (kbar) P= -0.20</div>
<div>-------------</div></div></div><div><br></div><div><br></div><div><br></div><div><div><p style="margin:0px 15px 15px;padding:0px;border:0px;outline:0px;font-size:12px;vertical-align:baseline;background-color:transparent;color:rgb(85,85,85);font-family:Helvetica,Osaka,'\00ff2d\00ff33 \00ff30\0030b4\0030b7\0030c3\0030af',Arial,sans-serif;line-height:18px">
Department of Applied Physics,<br>Graduate School of Engineering/Faculty of Engineering,<br>The University of Tokyo</p><p style="margin:0px 15px 15px;padding:0px;border:0px;outline:0px;font-size:12px;vertical-align:baseline;background-color:transparent;color:rgb(85,85,85);font-family:Helvetica,Osaka,'\00ff2d\00ff33 \00ff30\0030b4\0030b7\0030c3\0030af',Arial,sans-serif;line-height:18px">
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