<div dir="auto">There is no LO-TO splitting in that paper, nor in the figure you've sent. LO-TO splitting is a very specific effect that happens at Gamma: At Gamma the LO and TO bands of graphene are degenerate.<div dir="auto"><br></div><div dir="auto">You can find an explanation of LO-TO splitting in any solid state book and a gazillion web sites, in any language. Have a look around, then please come back to the forum if you have some specific question. <div dir="auto"><br></div><div dir="auto">Kind regards </div><div dir="auto"><br><br><div data-smartmail="gmail_signature" dir="auto">-- <br>Lorenzo Paulatto<br>Written on a virtual keyboard with real fingers</div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On 4 Dec 2017 1:33 pm, "Barnali Bhattacharya" <<a href="mailto:barnalidgbhatt@gmail.com" target="_blank">barnalidgbhatt@gmail.com</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Dear <span style="font-size:12.8px">Lorenzo Paulatto,</span><div><span style="font-size:12.8px"><br></span></div><div><span style="font-family:"Helvetica Neue",Arial,sans-serif;font-size:15px">Thank you for your reply. But recently I have gone your Physical review paper (</span><span style="color:rgb(0,0,0);font-family:Times-Roman;font-size:9pt">PHYSICAL REVIEW B </span><span style="color:rgb(0,0,0);font-size:9pt;font-family:Times-Bold"><b>87</b><span style="font-family:Times-Roman;font-size:9pt">, 214303 (2013)</span></span></div><div><span style="font-family:"Helvetica Neue",Arial,sans-serif;font-size:15px">) where you have shown phonon dispersion with LO-TO splitting for graphene (Figure 2) in page </span><span style="color:rgb(0,0,0);font-family:Times-Roman;font-size:9pt">214303-4.</span></div><div><span style="color:rgb(0,0,0);font-family:Times-Roman;font-size:9pt"><br></span></div><div><span style="color:rgb(0,0,0);font-family:Times-Roman;font-size:9pt">"</span><span style="color:rgb(0,0,0);font-family:Times-Roman;font-size:10pt">Figure </span><span style="font-family:Times-Roman;font-size:10pt;color:rgb(0,0,255)">2 <span style="font-size:10pt;color:rgb(0,0,0)">shows the calculated graphene phonon dispersion,</span></span></div><span style="font-family:Times-Roman;font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt;color:rgb(0,0,255)"><span style="font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt">the respective anharmonic broadening and the vibrational<br><span style="font-size:10pt">density of states (VDOS). The branches are labeled in the usual<br><span style="font-size:10pt">way.<span style="font-size:7pt;color:rgb(0,0,255)">25 <span style="font-size:10pt;color:rgb(0,0,0)">There are three acoustic branches (ZA, TA, LA) and<br><span style="font-size:10pt">three optical branches (ZO, TO, LO). ZA and ZO correspond<br><span style="font-size:10pt">to an atomic motion perpendicular to the graphene plane (<span style="font-family:MTMI;font-size:10pt"><i>z</i><br><span style="font-family:Times-Roman;font-size:10pt">direction), all the other branches are polarized parallel to the<br><span style="font-size:10pt">plane."</span></span></span></span></span></span></span></span></span></span></span></span></span><div><span style="font-family:Times-Roman;font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt;color:rgb(0,0,255)"><span style="font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt"><span style="font-size:10pt"><span style="font-size:10pt"><br></span></span></span></span></span></span></div><div><span style="font-family:Times-Roman;font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt;color:rgb(0,0,255)"><span style="font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt"><span style="font-size:10pt"><span style="font-size:10pt">Being motivated by work I want to reproduce this curve. Please guide me.</span></span></span></span></span></span></div><div><span style="font-family:Times-Roman;font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt;color:rgb(0,0,255)"><span style="font-size:10pt;color:rgb(0,0,0)"><span style="font-size:10pt"><span style="font-size:10pt"><span style="font-size:10pt"><br></span></span></span></span></span></span></div><div>Thanking you </div><div><p class="m_-5455250114413658521gmail-MsoNormal" style="margin-bottom:0.0001pt;font-size:12.8px;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Barnali Bhattacharya</font></span></p><p class="m_-5455250114413658521gmail-MsoNormal" style="margin-bottom:0.0001pt;font-size:12.8px;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">CSIR SRF, Assam University,</font></span></p><p class="m_-5455250114413658521gmail-MsoNormal" style="margin-bottom:0.0001pt;font-size:12.8px;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Silchar-788011</font></span></p><p class="m_-5455250114413658521gmail-MsoNormal" style="margin-bottom:0.0001pt;font-size:12.8px;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Assam, INDIA</font></span></p></div><div><div><br></div></div><img width="0" height="0" id="m_-5455250114413658521shtracking_rm" src="https://app.saleshandy.com/web/email/countopened/4065967?userid=18781" style="display:none"></div><div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 1, 2017 at 12:03 AM, Lorenzo Paulatto <span dir="ltr"><<a href="mailto:paulatz@gmail.com" target="_blank">paulatz@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div>Dear Barnali,</div><div dir="auto">There is no LO-TO splitting in graphene, or more precisely, it is zero.</div><div dir="auto"><br></div><div dir="auto">Kind regards<br><br><div data-smartmail="gmail_signature" dir="auto">-- <br>Lorenzo Paulatto<br>Written on a virtual keyboard with real fingers</div><div class="gmail_extra" dir="auto"><br><div class="gmail_quote"><div><div class="m_-5455250114413658521h5">On 30 Nov 2017 3:59 pm, "Barnali Bhattacharya" <<a href="mailto:barnalidgbhatt@gmail.com" target="_blank">barnalidgbhatt@gmail.com</a>> wrote:<br type="attribution"></div></div><blockquote class="m_-5455250114413658521m_1356366889201788215quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_-5455250114413658521h5"><div dir="ltr"><p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="color:black"><font face="times new roman, serif">Dear QE USERS,<span></span></font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="color:black"><span><font face="times new roman, serif"> </font></span></span></p>
<pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">I am trying to reproduce the </span>phonon dispersion with <span style="color:black">LO-TO splitting of graphene </span><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">by using quantum espresso code.</span> </font></pre><pre><font face="times new roman, serif">To get LO-TO splitting, I have <span style="color:black">added epsil=.true. as well as </span>zeu=.true. in the input file of ph.x. </font>and calculated the phonon modes at q=0 (gamma point). </pre><pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">Then I have used dynmat.x. for getting </span><span style="color:black">LO-TO splitting. </span></font></pre><pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">At first, I did not added the propagation direction for q in the input file of dynmat.x .</span></font></pre><pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"> </span><span style="color:black">After running dynmat.x, it gives the following line in the output </span></font></pre><pre>……………………………………………………..</pre><pre><font face="times new roman, serif">A direction for q was not specified:TO-LO splitting will be absent</font></pre><pre>…………………………………………….</pre>
<pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">Then I specify</span><span style="color:black"> the q-point like <span></span></span></font></pre><pre><font face="times new roman, serif"><span style="color:black">q(1)=0.01, q(2)=0.0, q(3)=0.00 </span><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">in the input file of dynmat.x . </span></font></pre><pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">As a result the above line disappear from the output and the </span><span style="color:black">output is something like that<span></span></span></font></pre><pre>………………………………………………………………………………<wbr>…………………………………….</pre>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif">Reading Dynamical Matrix from file dmat.gra<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> ...Force constants read<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> ...epsilon and Z* read<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> Acoustic Sum Rule: || Z*(ASR) - Z*(orig)|| = 2.089033E-02<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> Acoustic Sum Rule: ||dyn(ASR) - dyn(orig)||= 1.397683E-04<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span><font face="times new roman, serif"> </font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> Polarizability (A^3 units)<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> multiply by 0.417318 for Clausius-Mossotti correction<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 25.389880 0.000000 0.000000<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 0.000000 25.389880 0.000000<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 0.000000 0.000000 1.110081<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span><font face="times new roman, serif"> </font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> IR activities are in (D/A)^2/amu units<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span><font face="times new roman, serif"> </font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"># mode [cm-1] [THz] IR<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 1 -0.00 -0.0000 0.0000<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 2 -0.00 -0.0000 0.0000<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 3 -0.00 -0.0000 0.0000<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 4 886.97 26.5907 0.0000<span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 5 1701.94 51.0228 0.0000</font></p><p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"> 6 1701.94 51.0228 0.0000</font></p><pre>………………………………………………………………………………<wbr>………………….</pre><pre><font face="times new roman, serif">So please tell me </font></pre><pre><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">1) from which file </span><span style="color:black">LO-TO splitting can be found?</span><br></font></pre>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span><font face="times new roman, serif"> </font></span></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">2) How can I get </span><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">the </span>phonon dispersion with <span style="color:black">LO-TO splitting of graphene?</span><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span></span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span><font face="times new roman, serif"> </font></span></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><font face="times new roman, serif"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"> I am waiting for </span><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial">any kind suggestions. For details, I am attaching here the input files and the dispersion curve which I want to reproduce?<span></span></span></font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span><font face="times new roman, serif"> </font></span></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Thanks in advance.<span></span></font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span><font face="times new roman, serif"> </font></span></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal;background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Sincerely </font></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Barnali Bhattacharya<span></span></font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">CSIR SRF, Assam University,<span></span></font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Silchar-788011<span></span></font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><font face="times new roman, serif">Assam, INDIA<span></span></font></span></p>
<p class="MsoNormal" style="margin-bottom:0.0001pt;line-height:normal"><span style="background-image:initial;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial"><span><font face="times new roman, serif"> </font></span></span></p>
<pre><span style="color:black"><font face="times new roman, serif"> </font></span></pre><img width="0" height="0" id="m_-5455250114413658521m_1356366889201788215m_6934357469405981494shtracking_18s" src="https://app.saleshandy.com/web/email/countopened/4026231?userid=18781" style="display:none"></div><div></div>
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