<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:16px"><div class="" style=""><span class="" style="">Dear Nicola,</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new york', times, serif; background-color: transparent; font-style: normal;" class=""><span class="" style="">Thank you for your replay,</span></div><div style="background-color: transparent;" class=""><span class="" style="">yes I've done the math with two atoms, but I'll make an alloy that is why I did it with 16 atoms.<br class="" style=""></span></div><div style="background-color: transparent; color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new york', times, serif; font-style: normal;" class=""><span class="" style=""><br></span></div><div style="background-color: transparent; color: rgb(0, 0, 0); font-size: 16px; font-family: 'times new roman', 'new
york', times, serif; font-style: normal;" class=""><span class="" style="">Asma</span></div><div style="background-color: transparent;" class=""><br></div><div class="" style=""><div style="font-family:garamond, 'new york', times, serif;font-size:16px;line-height:normal;background-color:transparent;font-style:italic;" class=""><br class="" style="">***********************************************</div><div style="line-height:normal;" class=""><span style="background-color:rgb(255, 255, 255);" class=""><span style="color:rgb(69, 69, 69);font-style:italic;" class=""><span style="font-family:garamond, 'new york', times, serif;font-size:16px;" class=""><span style="color:rgb(0, 0, 0);font-style:normal;" class=""><span style="font-style:italic;" class="">Said Asma,</span></span><span style="color:rgb(0, 0, 0);font-style:normal;" class=""><span style="font-style:italic;" class=""> </span></span></span></span></span></div><div
style="line-height:normal;color:rgb(0, 0, 0);font-size:16px;font-family:garamond, 'new york', times, serif;background-color:transparent;font-style:italic;" class=""><span style="background-color:rgb(255, 255, 255);" class=""><span style="color:rgb(69, 69, 69);font-style:italic;" class=""><span style="font-family:garamond, 'new york', times, serif;font-size:16px;" class=""><span style="color:rgb(0, 0, 0);font-style:normal;" class="">PhD. LMCN,</span></span></span></span></div><div style="line-height:normal;color:rgb(0, 0, 0);font-size:16px;font-family:garamond, 'new york', times, serif;background-color:transparent;font-style:normal;" class=""><span style="background-color:rgb(255, 255, 255);" class=""><span style="color:rgb(69, 69, 69);font-style:italic;" class=""><span style="font-family:garamond, 'new york', times, serif;font-size:16px;" class=""><span style="color:rgb(0, 0, 0);font-style:normal;" class=""><font class="" style="">Faculté des sciences
de Monastir,</font></span></span><br class="" style=""></span><span style="font-style:italic;font-family:garamond, 'new york', times, serif;font-size:16px;" class="">Avenue de l'environnement 5019-Monastir,Tunisie</span></span></div><div class="" style=""><span style="background-color:rgb(255, 255, 255);" class=""><span style="font-size:16px;line-height:normal;font-style:italic;font-family:garamond, 'new york', times, serif;" class="">E-mail :<a rel="nofollow" class="" style="" href="">saidasma1987@yahoo.fr</a></span></span></div><div class="" style=""><span style="background-color:rgb(255, 255, 255);font-family:garamond, 'new york', times, serif;font-size:16px;" class="">***********************************************</span></div></div> <div class="qtdSeparateBR"><br><br></div><div class="yahoo_quoted" style="display: block;"> <div style="font-family: times new roman, new york, times, serif; font-size: 16px;" class=""> <div style="font-family:
HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 12px;" class=""> <div dir="ltr" class="" style=""> <font size="2" face="Arial" class="" style=""> Le Mardi 30 septembre 2014 17h43, Nicola Marzari <nicola.marzari@epfl.ch> a écrit :<br class="" style=""> </font> </div> <br class="" style=""><br class="" style=""> <div class="" style=""><br clear="none" class="" style=""><br clear="none" class="" style="">Dear Said,<br clear="none" class="" style=""><br clear="none" class="" style=""><br clear="none" class="" style="">do the calculations with the primitive, 2-atom unit cell, on a mesh<br clear="none" class="" style="">of q-points, and plot the phonon dispersions. Otherwise in your supercell<br clear="none" class="" style="">the phonon branches get folded from the zone boundary to Gamma.<br clear="none" class="" style=""><br clear="none" class="" style="">In the limit of q->0, you'll see three linear
dispersions - two are <br clear="none" class="" style="">degenerate<br clear="none" class="" style="">and lower (the TA), one is higher (the LA). Check that they all go to zero<br clear="none" class="" style="">at q=0. Also, google "rocksalt phonon".<br clear="none" class="" style=""><br clear="none" class="" style=""> nicola<br clear="none" class="" style=""><br clear="none" class="" style=""><div class="" id="yqtfd82498" style=""><br clear="none" class="" style="">On 30/09/2014 18:25, Said Asma wrote:<br clear="none" class="" style="">> Dear QE users ans developers,<br clear="none" class="" style="">><br clear="none" class="" style="">><br clear="none" class="" style="">> I'm a beginner in the calculation of phonons.<br clear="none" class="" style="">> I did the phonons calculation of the binary AlN (rocksalt) with 16 atoms .<br clear="none" class="" style="">><br
clear="none" class="" style="">> My output files is as following:<br clear="none" class="" style="">><br clear="none" class="" style="">> Diagonalizing the dynamical matrix<br clear="none" class="" style="">><br clear="none" class="" style="">> q = ( 0.000000000 0.000000000 0.000000000 )<br clear="none" class="" style="">><br clear="none" class="" style="">> **************************************************************************<br clear="none" class="" style="">> freq ( 1) = 1.108833 [THz] = 36.986674 [cm-1]<br clear="none" class="" style="">> freq ( 2) = 1.574620 [THz] = 52.523675 [cm-1]<br clear="none" class="" style="">> freq ( 3) = 1.575398 [THz] =
52.549629 [cm-1]<br clear="none" class="" style="">> freq ( 4) = 8.195754 [THz] = 273.380916 [cm-1]<br clear="none" class="" style="">> freq ( 5) = 8.196815 [THz] = 273.416304 [cm-1]<br clear="none" class="" style="">> freq ( 6) = 8.199734 [THz] = 273.513674 [cm-1]<br clear="none" class="" style="">> freq ( 7) = 8.200351 [THz] = 273.534269 [cm-1]<br clear="none" class="" style="">> freq ( 8) = 8.201724 [THz] = 273.580054 [cm-1]<br clear="none" class="" style="">> freq ( 9) = 8.204042 [THz] = 273.657390 [cm-1]<br clear="none" class=""
style="">> freq ( 10) = 8.204069 [THz] = 273.658277 [cm-1]<br clear="none" class="" style="">> freq ( 11) = 8.204305 [THz] = 273.666167 [cm-1]<br clear="none" class="" style="">> freq ( 12) = 9.560810 [THz] = 318.914296 [cm-1]<br clear="none" class="" style="">> freq ( 13) = 9.561375 [THz] = 318.933138 [cm-1]<br clear="none" class="" style="">> freq ( 14) = 9.564736 [THz] = 319.045240 [cm-1]<br clear="none" class="" style="">> freq ( 15) = 9.565551 [THz] = 319.072451 [cm-1]<br clear="none" class="" style="">> freq ( 16) =
9.568429 [THz] = 319.168422 [cm-1]<br clear="none" class="" style="">> freq ( 17) = 9.569095 [THz] = 319.190663 [cm-1]<br clear="none" class="" style="">> freq ( 18) = 12.351077 [THz] = 411.987578 [cm-1]<br clear="none" class="" style="">> freq ( 19) = 12.431223 [THz] = 414.660977 [cm-1]<br clear="none" class="" style="">> freq ( 20) = 12.439828 [THz] = 414.947983 [cm-1]<br clear="none" class="" style="">> freq ( 21) = 12.782122 [THz] = 426.365702 [cm-1]<br clear="none" class="" style="">> freq ( 22) = 12.796523 [THz] = 426.846069 [cm-1]<br clear="none" class=""
style="">> freq ( 23) = 12.854425 [THz] = 428.777481 [cm-1]<br clear="none" class="" style="">> freq ( 24) = 12.908753 [THz] = 430.589665 [cm-1]<br clear="none" class="" style="">> freq ( 25) = 12.916648 [THz] = 430.852986 [cm-1]<br clear="none" class="" style="">> freq ( 26) = 12.923203 [THz] = 431.071665 [cm-1]<br clear="none" class="" style="">> freq ( 27) = 12.940057 [THz] = 431.633836 [cm-1]<br clear="none" class="" style="">> freq ( 28) = 12.951841 [THz] = 432.026913 [cm-1]<br clear="none" class="" style="">> freq ( 29) =
13.043933 [THz] = 435.098776 [cm-1]<br clear="none" class="" style="">> freq ( 30) = 13.090098 [THz] = 436.638683 [cm-1]<br clear="none" class="" style="">> freq ( 31) = 13.091268 [THz] = 436.677691 [cm-1]<br clear="none" class="" style="">> freq ( 32) = 16.509761 [THz] = 550.706361 [cm-1]<br clear="none" class="" style="">> freq ( 33) = 16.566717 [THz] = 552.606181 [cm-1]<br clear="none" class="" style="">> freq ( 34) = 16.587373 [THz] = 553.295203 [cm-1]<br clear="none" class="" style="">> freq ( 35) = 16.640103 [THz] = 555.054089 [cm-1]<br clear="none" class=""
style="">> freq ( 36) = 16.658006 [THz] = 555.651280 [cm-1]<br clear="none" class="" style="">> freq ( 37) = 16.692001 [THz] = 556.785223 [cm-1]<br clear="none" class="" style="">> freq ( 38) = 19.936035 [THz] = 664.994532 [cm-1]<br clear="none" class="" style="">> freq ( 39) = 19.939099 [THz] = 665.096767 [cm-1]<br clear="none" class="" style="">> freq ( 40) = 19.940916 [THz] = 665.157356 [cm-1]<br clear="none" class="" style="">> freq ( 41) = 19.955181 [THz] = 665.633197 [cm-1]<br clear="none" class="" style="">> freq ( 42) =
21.966886 [THz] = 732.736442 [cm-1]<br clear="none" class="" style="">> freq ( 43) = 21.984557 [THz] = 733.325899 [cm-1]<br clear="none" class="" style="">> freq ( 44) = 22.013871 [THz] = 734.303712 [cm-1]<br clear="none" class="" style="">> freq ( 45) = 22.697394 [THz] = 757.103583 [cm-1]<br clear="none" class="" style="">> freq ( 46) = 22.729742 [THz] = 758.182599 [cm-1]<br clear="none" class="" style="">> freq ( 47) = 22.771292 [THz] = 759.568539 [cm-1]<br clear="none" class="" style="">> freq ( 48) = 22.788849 [THz] = 760.154171 [cm-1]<br clear="none" class=""
style="">> ***********************************************************************<br clear="none" class="" style="">><br clear="none" class="" style="">> It has 16 atoms then we have 48 frequencies, 3 acoustic (which tend to<br clear="none" class="" style="">> 0) and 46 optical frenquencies, but how can I differentiate between<br clear="none" class="" style="">> longitudinal and transverse waves frequency?<br clear="none" class="" style="">> I looked at the file occurs, I found the displacements of atoms, but I<br clear="none" class="" style="">> was not able to distinguish between transeverse and longitudinal<br clear="none" class="" style="">> optical modes.<br clear="none" class="" style="">><br clear="none" class="" style="">> Below is an example of the frequencies in the dynamical matrix file :<br clear="none" class="" style="">><br clear="none" class="" style="">> freq (
4) = 8.195754 [THz] = 273.380916 [cm-1]<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.044678 0.000000 0.044678 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.002637 0.000000 -0.002637 0.000000 )<br clear="none" class="" style="">> ( -0.164130 0.000000 0.393942 0.000000 -0.051695 0.000000 )<br clear="none" class="" style="">> ( 0.005529 0.000000 0.003753 0.000000 0.001833 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.229388 0.000000 -0.229388 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.001731 0.000000 -0.001731 0.000000 )<br clear="none" class="" style="">> ( -0.167162 0.000000
-0.054230 0.000000 0.438521 0.000000 )<br clear="none" class="" style="">> ( 0.003854 0.000000 -0.000832 0.000000 -0.004534 0.000000 )<br clear="none" class="" style="">> ( 0.164130 0.000000 0.051695 0.000000 -0.393942 0.000000 )<br clear="none" class="" style="">> ( -0.005529 0.000000 -0.001833 0.000000 -0.003753 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.188464 0.000000 0.188464 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.006472 0.000000 -0.006472 0.000000 )<br clear="none" class="" style="">> ( 0.167162 0.000000 -0.438521 0.000000 0.054230 0.000000 )<br clear="none" class="" style="">> ( -0.003854 0.000000 0.004534 0.000000
0.000832 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.041543 0.000000 -0.041543 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.004383 0.000000 -0.004383 0.000000 )<br clear="none" class="" style="">> freq ( 5) = 8.196815 [THz] = 273.416304 [cm-1]<br clear="none" class="" style="">> ( 0.553586 0.000000 -0.066816 0.000000 -0.066816 0.000000 )<br clear="none" class="" style="">> ( -0.022611 0.000000 -0.004384 0.000000 -0.004384 0.000000 )<br clear="none" class="" style="">> ( -0.050218 0.000000 -0.248855 0.000000 -0.082446 0.000000 )<br clear="none" class="" style="">> ( -0.000781 0.000000 0.002840 0.000000 0.001799 0.000000
)<br clear="none" class="" style="">> ( -0.187313 0.000000 -0.127347 0.000000 -0.127347 0.000000 )<br clear="none" class="" style="">> ( 0.002035 0.000000 -0.000907 0.000000 -0.000907 0.000000 )<br clear="none" class="" style="">> ( 0.049241 0.000000 0.085657 0.000000 0.277200 0.000000 )<br clear="none" class="" style="">> ( -0.004321 0.000000 -0.001756 0.000000 -0.007275 0.000000 )<br clear="none" class="" style="">> ( -0.050218 0.000000 -0.082446 0.000000 -0.248855 0.000000 )<br clear="none" class="" style="">> ( -0.000781 0.000000 0.001799 0.000000 0.002840 0.000000 )<br clear="none" class="" style="">> ( 0.148869 0.000000 0.104419 0.000000 0.104419 0.000000 )<br clear="none" class="" style="">>
( -0.007221 0.000000 -0.002029 0.000000 -0.002029 0.000000 )<br clear="none" class="" style="">> ( 0.049241 0.000000 0.277200 0.000000 0.085657 0.000000 )<br clear="none" class="" style="">> ( -0.004321 0.000000 -0.007275 0.000000 -0.001756 0.000000 )<br clear="none" class="" style="">> ( -0.498090 0.000000 0.065208 0.000000 0.065208 0.000000 )<br clear="none" class="" style="">> ( 0.005159 0.000000 -0.002368 0.000000 -0.002368 0.000000 )<br clear="none" class="" style="">> freq ( 6) = 8.199734 [THz] = 273.513674 [cm-1]<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.016697 0.000000 0.016697 0.000000 )<br clear="none" class="" style="">> ( 0.000000
0.000000 -0.011124 0.000000 0.011124 0.000000 )<br clear="none" class="" style="">> ( -0.282827 0.000000 -0.268330 0.000000 -0.074618 0.000000 )<br clear="none" class="" style="">> ( 0.007226 0.000000 -0.003886 0.000000 0.008910 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.305360 0.000000 -0.305360 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.007286 0.000000 0.007286 0.000000 )<br clear="none" class="" style="">> ( -0.279901 0.000000 -0.077837 0.000000 -0.279063 0.000000 )<br clear="none" class="" style="">> ( 0.009124 0.000000 -0.007508 0.000000 0.003791 0.000000 )<br clear="none" class="" style="">> ( 0.282827 0.000000 0.074618
0.000000 0.268330 0.000000 )<br clear="none" class="" style="">> ( -0.007226 0.000000 -0.008910 0.000000 0.003886 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.292826 0.000000 0.292826 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.001182 0.000000 0.001182 0.000000 )<br clear="none" class="" style="">> ( 0.279901 0.000000 0.279063 0.000000 0.077837 0.000000 )<br clear="none" class="" style="">> ( -0.009124 0.000000 -0.003791 0.000000 0.007508 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 0.019674 0.000000 -0.019674 0.000000 )<br clear="none" class="" style="">> ( 0.000000 0.000000 -0.004853 0.000000
0.004853 0.000000 )<br clear="none" class="" style="">><br clear="none" class="" style="">><br clear="none" class="" style="">> with respectful regards<br clear="none" class="" style="">><br clear="none" class="" style="">> ***********************************************<br clear="none" class="" style="">> Said Asma,<br clear="none" class="" style="">> PhD. LMCN,<br clear="none" class="" style="">> Faculté des sciences de Monastir,<br clear="none" class="" style="">> Avenue de l'environnement 5019-Monastir,Tunisie<br clear="none" class="" style="">> E-mail :<a shape="rect" ymailto="mailto:saidasma1987@yahoo.fr" href="mailto:saidasma1987@yahoo.fr" class="" style="">saidasma1987@yahoo.fr</a></div><br clear="none" class="" style="">> ***********************************************<br clear="none" class="" style="">><br clear="none" class="" style="">><br clear="none" class="" style="">>
_______________________________________________<br clear="none" class="" style="">> Pw_forum mailing list<br clear="none" class="" style="">> <a shape="rect" ymailto="mailto:Pw_forum@pwscf.org" href="mailto:Pw_forum@pwscf.org" class="" style="">Pw_forum@pwscf.org</a><br clear="none" class="" style="">> <a shape="rect" href="http://pwscf.org/mailman/listinfo/pw_forum" target="_blank" class="" style="">http://pwscf.org/mailman/listinfo/pw_forum</a><br clear="none" class="" style="">><br clear="none" class="" style=""><br clear="none" class="" style="">-- <br clear="none" class="" style=""><br clear="none" class="" style="">----------------------------------------------------------------------<br clear="none" class="" style="">Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL<div class="" id="yqtfd11175" style=""><br clear="none" class="" style=""></div><br class="" style=""><br class="" style=""></div> </div> </div>
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