[QE-users] Question about Superconducting Properties using lambda.x

[Manish Kumar]

Hello QE users and experts.
I am using Quantum-Espresso to compute electron-phonon coupling and other
superconducting properties for a material at different pressures. My first
SCF run uses a dense k-grid of 48x48x48 which would include all the k and
k+q points. Subsequent phonon calculations are performed with a relatively
coarse but well converged k-grid of 12x12x12 and a q-grid of 6x6x6.
The graph showing values of different superconducting properties w.r.t.
different broadening has been attached with this email. From the graph, can
I claim that my results are converging? How do I select the *range *of
broadening values for testing the convergence of these SC properties?
One more thing, during the intermediate steps while performing these
calculations, I noticed a 'strange thing(!)'. The file *lambda* that is
generated after the successful computation of *matdyn.dos.in
<http://matdyn.dos.in/>* and the output file of *lambda.in
<http://lambda.in/>* have very different values of *omega_ln* and
*<log w>*  are
very different. Is it supposed to be like this? Or is it indicating that
the values of broadening that I have used are not good for integration over
the fermi surface?

*Input/Output Files mentioned in the body of the email:*
*matdyn.dos.in <http://matdyn.dos.in/>*
*&INPUT*
*asr ='crystal'*
*flfrc ='Na2ZnH6.fc'*
*flfrq = 'Phdos.freq'*
*la2F=.true.*
*dos = .true.*
*fldos='phdos.dat'*
*flvec = 'Na2ZnH6.modes'*
*amass(1) = 1.007940 *
*amass(2) = 22.989769 *
*amass(3) =  65.380*
*nk1=18*
*nk2=18*
*nk3=18*
*/*

*lambda*
*  Electron-phonon coupling constant, lambda *

* Broadening   0.0010 lambda       2.1330 dos(Ef)  9.4719 omega_ln [K]
410.1623*
* Broadening   0.0020 lambda       1.8484 dos(Ef)  9.2938 omega_ln [K]
398.7419*
* Broadening   0.0030 lambda       1.6873 dos(Ef)  9.2716 omega_ln [K]
395.2356*
* Broadening   0.0040 lambda       1.6140 dos(Ef)  9.2094 omega_ln [K]
391.4003*
* Broadening   0.0050 lambda       1.5727 dos(Ef)  9.1464 omega_ln [K]
388.6757*
* Broadening   0.0060 lambda       1.5467 dos(Ef)  9.0927 omega_ln [K]
387.0169*
* Broadening   0.0070 lambda       1.5297 dos(Ef)  9.0536 omega_ln [K]
386.0194*
* Broadening   0.0080 lambda       1.5184 dos(Ef)  9.0286 omega_ln [K]
385.3719*
* Broadening   0.0090 lambda       1.5108 dos(Ef)  9.0167 omega_ln [K]
384.8943*
* Broadening   0.0100 lambda       1.5061 dos(Ef)  9.0179 omega_ln [K]
384.4926*

*lambda.in <http://lambda.in/>*
*41 0.02 1*
*16*
*  0.0000000  0.0000000  0.0000000   1.00*
* -0.1666667 -0.1666667  0.1666667   8.00*
* -0.3333333 -0.3333333  0.3333333   8.00*
* -0.5000000 -0.5000000  0.5000000   4.00*
*  0.0000000  0.0000000  0.3333333   6.00*
* -0.1666667 -0.1666667  0.5000000  24.00*
* -0.3333333 -0.3333333  0.6666667  24.00*
* -0.5000000 -0.5000000  0.8333333  24.00*
* -0.6666667 -0.6666667  1.0000000  12.00*
*  0.0000000  0.0000000  0.6666667   6.00*
* -0.1666667 -0.1666667  0.8333333  24.00*
* -0.3333333 -0.3333333  1.0000000  12.00*
*  0.0000000  0.0000000  1.0000000   3.00*
* -0.3333333 -0.0000000  0.6666667  24.00*
* -0.5000000 -0.1666667  0.8333333  24.00*
* -0.3333333  0.0000000  1.0000000  12.00*
*elph_dir/elph.inp_lambda.1 *
*elph_dir/elph.inp_lambda.2 *
*elph_dir/elph.inp_lambda.3 *
*elph_dir/elph.inp_lambda.4 *
*elph_dir/elph.inp_lambda.5 *
*elph_dir/elph.inp_lambda.6 *
*elph_dir/elph.inp_lambda.7 *
*elph_dir/elph.inp_lambda.8 *
*elph_dir/elph.inp_lambda.9 *
*elph_dir/elph.inp_lambda.10 *
*elph_dir/elph.inp_lambda.11 *
*elph_dir/elph.inp_lambda.12 *
*elph_dir/elph.inp_lambda.13 *
*elph_dir/elph.inp_lambda.14 *
*elph_dir/elph.inp_lambda.15 *
*elph_dir/elph.inp_lambda.16*
*0.15*

*lambda.out*
*     lambda = 2.383066 (   3.106094 )  <log w>=  548.184 K  N(Ef)=
9.471860 at degauss= 0.001*
*     lambda = 1.952337 (   2.387304 )  <log w>=  522.568 K  N(Ef)=
9.293815 at degauss= 0.002*
*     lambda = 1.754108 (   2.170817 )  <log w>=  516.508 K  N(Ef)=
9.271559 at degauss= 0.003*
*     lambda = 1.676906 (   2.097600 )  <log w>=  513.796 K  N(Ef)=
9.209398 at degauss= 0.004*
*     lambda = 1.635858 (   2.054322 )  <log w>=  512.822 K  N(Ef)=
9.146440 at degauss= 0.005*
*     lambda = 1.610377 (   2.026355 )  <log w>=  513.018 K  N(Ef)=
9.092700 at degauss= 0.006*
*     lambda = 1.593949 (   2.008835 )  <log w>=  513.490 K  N(Ef)=
9.053555 at degauss= 0.007*
*     lambda = 1.583606 (   1.998571 )  <log w>=  514.075 K  N(Ef)=
9.028563 at degauss= 0.008*
*     lambda = 1.577008 (   1.991954 )  <log w>=  514.631 K  N(Ef)=
9.016710 at degauss= 0.009*
*     lambda = 1.573685 (   1.988960 )  <log w>=  515.193 K  N(Ef)=
9.017930 at degauss= 0.010*
*lambda        omega_log          T_c*
*   2.38307       548.184             79.448*
*   1.95234       522.568             65.497*
*   1.75411       516.508             58.971*
*   1.67691       513.796             56.194*
*   1.63586       512.822             54.721*
*   1.61038       513.018             53.871*
*   1.59395       513.490             53.350*
*   1.58361       514.075             53.048*
*   1.57701       514.631             52.872*
*   1.57369       515.193             52.812*


-- 

*Manish Kumar*

*Ph.D. Scholar*

*Department of Computational Sciences,*

*Central University of Punjab,*

*VPO-Ghudda, Bathinda Punjab, India- 151401*
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