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Dear QE users,</div>
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I am trying to calculate MgB2 superconducting Tc with lambda.x. As I understand it, the correct value will be the one that is converged with respect to sigma value (within plateau). However, I get a strange results without getting any plateau and therefore
can't pick the correct value. Values of sigma are default (from 0.005 to 0.1). The output of lamda.x is given below:<br>
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lambda omega_log T_c
<div class="ContentPasted0"> 0.69701 640.588 22.047</div>
<div class="ContentPasted0"> 0.74121 644.652 25.642</div>
<div class="ContentPasted0"> 0.72855 644.807 24.658</div>
<div class="ContentPasted0"> 0.71480 644.406 23.568</div>
<div class="ContentPasted0"> 0.70317 644.049 22.646</div>
<div class="ContentPasted0"> 0.68885 644.102 21.531</div>
<div class="ContentPasted0"> 0.67095 644.454 20.150</div>
<div class="ContentPasted0"> 0.65095 645.095 18.622</div>
<div class="ContentPasted0"> 0.63044 645.881 17.069</div>
<div class="ContentPasted0 elementToProof"> 0.61045 646.888 15.579</div>
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<div class="ContentPasted0 elementToProof">I will really appreciate if QE users/experts can help me resolve this problem or highlight the correct procedure of picking Tc value.
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<div class="ContentPasted0 elementToProof">Both scf and phonon calculations are nicely converged so I don't think convergence is a problem. Input for scf and phonon calculations are given below:</div>
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<div class="ContentPasted0 elementToProof"><b><u><i>scf</i></u></b><br>
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<div class="ContentPasted0 elementToProof ContentPasted1"> &control
<div class="ContentPasted1"> calculation='scf',</div>
<div class="ContentPasted1"> prefix='MgB2',</div>
<div class="ContentPasted1"> pseudo_dir = '~/pseudo/',</div>
<div class="ContentPasted1"> outdir='./save/',</div>
<div class="ContentPasted1"> tprnfor = .true.,</div>
<div class="ContentPasted1"> tstress = .true.,</div>
<div class="ContentPasted1"> etot_conv_thr = 1.0d-5</div>
<div class="ContentPasted1"> forc_conv_thr = 1.0d-4</div>
<div class="ContentPasted1"> /</div>
<div class="ContentPasted1"> &system</div>
<div class="ContentPasted1"> ibrav = 4,</div>
<div class="ContentPasted1"> celldm(1) = 5.8260252227888,</div>
<div class="ContentPasted1"> celldm(3) = 1.1420694129095,</div>
<div class="ContentPasted1"> nat= 3,</div>
<div class="ContentPasted1"> ntyp = 2,</div>
<div class="ContentPasted1"> ecutwfc = 100</div>
<div class="ContentPasted1"> smearing = 'mp'</div>
<div class="ContentPasted1"> occupations = 'smearing'</div>
<div class="ContentPasted1"> degauss = 0.02</div>
<div class="ContentPasted1">la2F = .true.,</div>
<div class="ContentPasted1"> /</div>
<div class="ContentPasted1"> &electrons</div>
<div class="ContentPasted1"> diagonalization = 'david'</div>
<div class="ContentPasted1"> mixing_mode = 'plain'</div>
<div class="ContentPasted1"> mixing_beta = 0.7</div>
<div class="ContentPasted1"> conv_thr = 1.0d-12</div>
<div class="ContentPasted1"> /</div>
<div class="ContentPasted1">ATOMIC_SPECIES</div>
<div class="ContentPasted1"> Mg 24.305 Mg.pz-n-vbc.UPF</div>
<div class="ContentPasted1"> B 10.811 B.pz-vbc.UPF</div>
<div class="ContentPasted1">ATOMIC_POSITIONS crystal</div>
<div class="ContentPasted1">Mg 0.000000000 0.000000000 0.000000000</div>
<div class="ContentPasted1">B 0.333333333 0.666666667 0.500000000</div>
<div class="ContentPasted1">B 0.666666667 0.333333333 0.500000000</div>
<div class="ContentPasted1">K_POINTS AUTOMATIC</div>
<div class="ContentPasted1">16 16 16 0 0 0</div>
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<div class="ContentPasted0 elementToProof"><u><b>phonon</b></u><br>
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<div class="ContentPasted0 elementToProof ContentPasted2">e-ph MgB2
<div class="ContentPasted2">&inputph</div>
<div class="ContentPasted2"> prefix = 'MgB2',</div>
<div class="ContentPasted2"> fildyn = 'MgB2.dyn',</div>
<div class="ContentPasted2"> amass(1) = 24.305,</div>
<div class="ContentPasted2"> amass(2) = 10.811,</div>
<div class="ContentPasted2"> outdir = './save/'</div>
<div class="ContentPasted2"> ldisp = .true.,</div>
<div class="ContentPasted2"> trans = .true.,</div>
<div class="ContentPasted2"> fildvscf = 'dvscf',</div>
<div class="ContentPasted2"> nq1=8, nq2=8, nq3=8,</div>
<div class="ContentPasted2"> tr2_ph = 1.0d-14</div>
<div class="ContentPasted2">electron_phonon='interpolated',</div>
<div class="ContentPasted2"> el_ph_sigma=0.005,</div>
<div class="ContentPasted2"> el_ph_nsigma=10,</div>
<div class="ContentPasted2"> /</div>
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