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<font face="Courier New">Dear all,</font><div><font face="Courier New"><br></font></div><div><font face="Courier New">I am trying to do el-ph calculations only at the Gamma point for graphene (as I want to compare it to another system where the calculations are only feasible at the Gamma point). However the values I am getting for lambda for graphene AT THE GAMMA POINT are really high:</font></div><div><br></div><div><p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New"">degauss lambda <o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New""> 0.005
13.442600 </span></p><p class="MsoPlainText"><span lang="PT-BR" style="font-family: 'Courier New'; "> 0.015 2.303600 <o:p></o:p></span></p><p class="MsoPlainText"><span lang="PT-BR" style="font-family: 'Courier New'; "> 0.020 1.756000</span><span style="font-family: 'Courier New'; font-size: 10pt; "> </span><span style="font-family: 'Courier New'; font-size: 10pt; "> </span></p>
<p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New""> 0.025
1.436000 <o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New""> 0.030
1.228800 <o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New""> 0.035
1.085800 <o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New""> 0.040
0.983000 <o:p></o:p></span></p>
<p class="MsoPlainText"><span lang="PT-BR" style="font-family:"Courier New""> 0.045
0.906400 <o:p></o:p></span></p>
<span lang="PT-BR" style="font-size:10.5pt;font-family:"Courier New";mso-fareast-font-family:
Calibri;mso-fareast-theme-font:minor-latin;mso-ansi-language:PT-BR;mso-fareast-language:
EN-US;mso-bidi-language:AR-SA">
0.050 0.847800</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">I am using a 90 x90 x1 grid (in scf) for graphene. </span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">It is already known that lambda for graphene is ~0.02. </span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">(1) Do the above results mean that one cannot calculate el-ph coefficients unless on a grid of phonons and then are the calculations -at the Gamma point ONLY- useless and unexact?</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">(2) or does this mean that the results did not converge due to a small k-mesh in the scf calculations (90x90x1) and I need to increase it to say 400x400x1?</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">Any suggestions of any kind would also be ahighly appreciated.</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">Thanks for your help</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">Elie M</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">University of Notts</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">NG7 2RD</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; ">UK</span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "><br></span></div><div><span style="font-family: 'Courier New'; font-size: 10.5pt; "> </span></div> </div></body>
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