<p>Dear all:</p><p>If one wants to evaluate the superconducting transition temperature<br>for a matrial, the last step is executing lambda.x. But I have a <br>question about the q-points and their sequence in the input file of<br>lambda.x. We can see these sentences "use kpoints.x program<br>to calculate q-points and their weight, elph output file names in<br>the same order as the q-points before" in the explanatory note<br>of run_example in example03 of QE-5.0.2. The time sequence of elph<br>output files calculated by ph.x are the same as the order of<br>q-points generated by ph.x. But the orders of q-points generated<br>by ph.x and kpoints.x are different (see appendix).<br>There are basicly three formats to write the input of lambda.x as<br>follows.</p><p>1. use the sequence and weights of q-points calculated by kpoints.x,<br>keep the time sequence of elph files generated by ph.x.<br>2. use the sequence and weights of q-points calculated by kpoints.x,<br>adjust the sequence of elph files according to that given by kpoints.x.<br>3. use the sequence and weights of q-points calculated by ph.x, keep<br>the time sequence of elph files generated by ph.x.</p><p><br>First time, I choose format-1 and can reproduce the properties<br>of MgB2, for example the electron-phonon coupling constant lambda=0.9,<br>the logarithmic average frequency omega_log=60.9 meV, and 39.9 K for Tc,<br>which are consistent with literatures.</p><p>But according to the explanatory note of run_example in example03,<br>the format-2 should be chosen, am I right?<br>Format-2 gives lambda=0.57, omega_log=62 meV, and 11.8 K for Tc in MgB2,<br>which seems not correct.<br>So I'm confused which format should I use?</p><p>By the way, has anyone reproduced the electron-phonon coupling for MgB2?</p><p>I am greatly indebted to you for your help. Thanks again!<br> <br>Best wishes<br> <br>Miao Gao<br>------------------<br>Ph.D. student of Department of Physics, <br>Renmin University of China.<br>------------------<br> &
nbsp; </p><p> </p><p> Appendix</p><p>The q-points on 6x6x6 mesh given by pw.x and ph.x are same with<br>each other, with the corresponding weights listed in the output of pw.x.<br>Following are the q-points and their weights given by pw.x/ph.x.<br>-------------------------------------------------------------<br> Dynamical matrices for ( 6, 6, 6) uniform grid of q-points<br> ( 28q-points):<br> N xq(1) xq(2) xq(3)<br> 1 0.000000000 0.000000000 0.000000000 1<br> 2 0.000000000 0.000000000 0.145024197 2<br> 3 0.000000000 0.000000000 0.290048395 2<br> 4 0.000000000 0.000000000 -0.435072592 1<br> 5 0.000000000 0.192450090 0.000000000 6<br> 6 0.000000000 0.192450090 0.145024197 12<br> 7 0.000000000 0.192450090 0.290048395 12<br> 8 0.000000000 0.192450090 -0.435072592 6<br> 9 
; 0.000000000 0.384900179 0.000000000 6<br> 10 0.000000000 0.384900179 0.145024197 12<br> 11 0.000000000 0.384900179 0.290048395 12<br> 12 0.000000000 0.384900179 -0.435072592 6<br> 13 0.000000000 -0.577350269 0.000000000 3<br> 14 0.000000000 -0.577350269 0.145024197 6<br> 15 0.000000000 -0.577350269 0.290048395 6<br> 16 0.000000000 -0.577350269 -0.435072592 3<br> 17 0.166666667 0.288675135 0.000000000 6<br> 18 0.166666667 0.288675135 0.145024197 12<br> 19 0.166666667 0.288675135 0.290048395 12<br> 20 0.166666667 0.288675135 -0.435072592 6<br> 21 0.166666667 0.481125224 0.000000000 12<br> 22 0.166666667 0.481125224 0.145024197 24<br> 23 0.166666667 0.481125224 0.290048395 24<br> 24 0.166666667 0.481125224 -0.435072592 12<br> 25 0.333333333 0.577350269 0.000000000 2<br> &n
bsp; 26 0.333333333 0.577350269 0.145024197 4<br> 27 0.333333333 0.577350269 0.290048395 4<br> 28 0.333333333 0.577350269 -0.435072592 2<br>-------------------------------------------------------------</p><p>The sequence and weight of q-points on 6x6x6 mesh given by kpoints.x.<br>-------------------------------------------------------------<br>0.0000000 0.0000000 0.0000000 1.00<br>0.1666667 0.0962250 0.0000000 6.00<br>0.3333333 0.1924501 0.0000000 6.00<br>0.5000000 0.2886751 0.0000000 3.00<br>0.1666667 0.2886751 0.0000000 6.00<br>0.3333333 0.3849002 0.0000000 12.00<br>0.3333333 0.5773503 0.0000000 2.00<br>0.0000000 0.0000000 0.1450242 2.00<br>0.1666667 0.0962250 0.1450242 12.00<br>0.3333333 0.1924501 0.1450242 12.00<br>0.5000000 0.2886751 0.1450242 6.00<br>0.1666667 0.2886751 0.1450242 12.00<br>0.3333333 0.3849002 0.1450242 24.00<br>0.3333333 0.5773503 0.1450242 4.00<br>0.0000000 0.0000000 0.2900484 2.00<br>0.1666667 0.0962250 0.2900484 12.00<br>0.3333333 0.1924501 0.2900484 12.00<br>0.5000000 0.2886751 0.2900484 6.00<br>0.1666667 0.2886751 0.2900484 12.00<br>0.3333333 0.3849002 0.2900484 24.00<br>0.3333333 0.5773503 0.2900484 4.00<br>0.0000000 0.0000000 0.4350726 1.00<br>0.1666667 0.0962250 0.4350726 6.00<br>0.3333333 0.1924501 0.4350726 6.00<br>0.5000000 0.2886751 0.4350726 3.00<b
r>0.1666667 0.2886751 0.4350726 6.00<br>0.3333333 0.3849002 0.4350726 12.00<br>0.3333333 0.5773503 0.4350726 2.00<br>-----------------------------------------------------------<br><br><br></p><span></span><br><br>