I have a question regrading the plot of superconducting gap of MgB2 in the EPW tutorial, namely figure 4 in the website http://epw.org.uk/Documentation/MgB2. To simplify my question, we just focus on the data at temp = 10 K.
To obtain the related data, I run EPW with the following setting
Code: Select all
laniso = .true.
limag = .true.
lpade = .true.
conv_thr_iaxis = 1.0d-4
wscut = 0.1
nstemp = 1
tempsmin = 10.00
tempsmax = 10.00
nsiter = 500
muc = 0.16
nk1 = 6
nk2 = 6
nk3 = 6
nq1 = 6
nq2 = 6
nq3 = 6
nkf1 = 20
nkf2 = 20
nkf3 = 20
nqf1 = 20
nqf2 = 20
nqf3 = 20
In my opinion, the data related to the plot contains in the file "MgB2.pade_aniso_gap0_010.00", consisting of two columns. The 1st line is related to the temperature and the 2nd line is related to the superconducting gap. For example, part of the file "MgB2.pade_aniso_gap0_010.00" is printed as follow:
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....
1.0286346327E+01 2.8150685314E-03
1.0369990290E+01 2.8200686531E-03
1.0064873023E+01 2.8250687748E-03
1.0001545623E+01 2.8300688965E-03
1.0000703414E+01 2.8350690183E-03
1.0032610942E+01 2.8400691400E-03
1.0259129394E+01 2.8450692617E-03
1.0530958890E+01 2.8500693834E-03
1.0280679142E+01 2.8550695052E-03
1.0025608716E+01 2.8600696269E-03
1.0010925964E+01 2.8650697486E-03
1.0155078076E+01 2.8700698703E-03
1.0411548208E+01 2.8750699921E-03
1.0383465780E+01 2.8800701138E-03
1.0371572717E+01 2.8850702355E-03
1.0160168949E+01 2.8900703572E-03
1.0013832215E+01 2.8950704790E-03
1.0000178533E+01 2.9000706007E-03
1.0000000318E+01 2.9050707224E-03
1.0000000002E+01 2.9100708441E-03
1.0000003555E+01 2.9150709659E-03
1.0000994098E+01 2.9200710876E-03
1.0037942087E+01 2.9250712093E-03
1.0221337382E+01 2.9300713310E-03
1.0494768483E+01 2.9350714528E-03
1.1000000000E+01 2.9400715745E-03
1.0844934498E+01 2.9450716962E-03
1.0347956585E+01 2.9500718179E-03
....
The figure 4 should be the histogram of the 2nd column according to the caption "For each temperature the histograms indicate the number of states on the Fermi surface with that superconducting gap energy". I can understand this when the 1st column are identical (e.g. =10 K). However, I find that though most temperatures in the 1st column are very close to 10 K, there are still a part exhibit a bit deviations from 10 K, as displayed above. I would like to know:
(1) Why there exist the above deviations. May be there is some problems with my calculations?
(2) I wonder if the data used to plot the figure as shown in the tutorial, have the similar feature, namely, the deviations from the target temperature of the 1st column. If it is the case, how to deal with those part of the data? Just skip them or enforce them to 10 K?
Bests!