[Wannier] CoSb3 BoltzWann
Giovanni Pizzi
giovanni.pizzi at epfl.ch
Fri Feb 13 18:52:56 CET 2015
Dear all,
just as a follow-up on the previous email: we have investigated the
issue with Yongsheng Zhang, and we realized that the discrepancy is due
to the different lattice constants used in the two calculations (which
in turn change significantly the bandgap).
As the (DFT) bandgap is very small for this material, even small changes
can significantly affect the Seebeck coefficient at room temperature due
to the different concentration of intrinsic carriers at a given chemical
potential, as it can be seen e.g. by a simple two-band model.
Giovanni
On 02/12/2015 10:43 PM, Giovanni Pizzi wrote:
> Dear Yongsheng Zhang,
> thank you for the data. Indeed, this looks very strange. The
> parameters seem correct.
> Your wpout file, though, seems weird to me, as there are some lines
> with missing characters, which makes me think of a possible
> miscompilation issue?
>
> I might need a couple of files more, let's continue this discussion
> offline.
>
> Giovanni
>
> --
> Giovanni Pizzi
> Post-doctoral Research Scientist
> EPFL STI IMX THEOS
> MXC 340 (Bâtiment MXC)
> Station 12
> CH-1015 Lausanne (Switzerland)
> Phone: +41 21 69 31124
>
>
>
>
> On 12 Feb 2015, at 18:18, Yongsheng Zhang wrote:
>
>> Dear Giovanni,
>>
>> Thanks for your quick response. I attach the band structure
>> comparison (band.pdf) between pwscf and the wannier interpolated, and
>> nearly all the input and output files in the pwscf and wannier90
>> calculations (boltz.tar.gz). The Fermi energy of CoSb3 is 8.16 eV.
>>
>> Thanks
>>
>> Yongsheng Zhang
>>
>> Materials Science and Engineering Department
>> Northwestern Univeristy
>>
>>
>> On Thursday, February 12, 2015 3:53 PM, Giovanni Pizzi
>> <giovanni.pizzi at epfl.ch <mailto:giovanni.pizzi at epfl.ch>> wrote:
>>
>>
>> Dear Yongsheng Zhang,
>>
>> it is difficult to say what is going on without also looking at your
>> resulting output file.
>> I did not check the crystal structure - but I guess it is right as
>> you say you are obtaining a good band structure.
>> The BoltzWann section seems ok at a first glance.
>>
>> The only comment I can give: did you check where is the Fermi energy
>> in your system? If you are using different pseudos or convergence
>> parameters, it may be different from the published results. Try to
>> check the band structure to see where the gap is and compare with the
>> band structure of Fig. 1 of the paper you mention (G. Pizzi et al. /
>> Computer Physics Communications 185 (2014) 422–429).
>> You can also plot a larger range for the chemical potential (changing
>> boltz_mu_min/max) to find the region around the gap.
>>
>> If this does not solve your problem, could you also post more
>> information (ab initio and interpolated band structure + output .wout
>> and .wpout + output Seebeck coefficient?)
>>
>> Thanks,
>> Giovanni
>>
>>
>> P.S.: Could you sign your posts with your affiliation? Thanks!
>>
>>
>> --
>> Giovanni Pizzi
>> Post-doctoral Research Scientist
>> EPFL STI IMX THEOS
>> MXC 340 (Bâtiment MXC)
>> Station 12
>> CH-1015 Lausanne (Switzerland)
>> Phone: +41 21 69 31124
>>
>>
>>
>>
>> On 12 Feb 2015, at 05:52, Yongsheng Zhang wrote:
>>
>>> Dear Wannier90,
>>>
>>> Recently, I am trying to learn how to use wannier90 to calculate the
>>> Boltzmann transport. Using the Si example (example 16) in the
>>> tutorial,I can successfully get the Seebeck coefficient of Si.
>>> Then, I turn to another compound, CoSb3, the BoltzWann test
>>> compound published in Computer Physics Communications. Following the
>>> procedures and using the same parameters, the Wannier90 interpolated
>>> band structures are in good agreement with the first-principles
>>> calculations (pwscf). And my band structure plot is the same as Fig.
>>> 1 in the published paper. So far, I think I didn't do anything
>>> wrong. In the next step, I run 'postw90.x' to calculate the
>>> transport distribution function (TDF) and the thermoelectric
>>> properties. Unfortunately, it turns out that my calculated Seebeck
>>> coefficient [S(mu)] is significantly different to the one in Fig. 4
>>> in the published paper. I am very confused. Please help me out. The
>>> following is the *.win file.
>>>
>>> Thanks
>>> Yongsheng Zhang
>>>
>>> !!! -- Begin of BoltzWann input -- !!!
>>> boltzwann = true
>>> boltz_calc_also_dos = true
>>> boltz_dos_energy_step = 0.01
>>> smr_type = gauss
>>> boltz_dos_adpt_smr = false
>>> boltz_dos_smr_fixed_en_width = 0.03
>>> kmesh = 40
>>> boltz_mu_min = 7.5
>>> boltz_mu_max = 9
>>> boltz_mu_step = 0.01
>>> boltz_temp_min = 200.
>>> boltz_temp_max = 1000.
>>> boltz_temp_step = 10
>>> boltz_relax_time = 10.
>>> !! Next variable is commented because 2 is its default value
>>> !num_elec_per_state = 2
>>> !!! --- End of BoltzWann input --- !!!
>>>
>>> #restart = plot
>>> #bands_plot = true
>>> #bands_plot_format = xmgr
>>>
>>> num_bands = 100
>>> num_wann = 56
>>> dis_win_max = 16.d0
>>> dis_win_min = 2.d0
>>> dis_froz_max = 9.5d0
>>> dis_froz_min = 2.0d0
>>> dis_num_iter = 120
>>> dis_mix_ratio = 1.d0
>>>
>>> num_iter = 500
>>> num_print_cycles = 50
>>>
>>> begin unit_cell_cart
>>> Ang
>>> 4.51926500000000 -4.51926500000000 -4.51926500000000
>>> 4.51926500000000 4.51926500000000 4.51926500000000
>>> -4.51926500000000 -4.51926500000000 4.51926500000000
>>> end unit_cell_cart
>>>
>>> begin atoms_frac
>>> Sb 0.66462600000000 0.15788400000000 0.82251000000000
>>> Sb 0.66462600000000 0.84211600000000 0.50674200000000
>>> Sb 0.33537400000000 0.15788400000000 0.49325800000000
>>> Sb 0.33537400000000 0.84211600000000 0.17749000000000
>>> Sb 0.15788400000000 0.49325800000000 0.33537400000000
>>> Sb 0.15788400000000 0.82251000000000 0.66462600000000
>>> Sb 0.82251000000000 0.66462600000000 0.15788400000000
>>> Sb 0.50674200000000 0.66462600000000 0.84211600000000
>>> Sb 0.17749000000000 0.33537400000000 0.84211600000000
>>> Sb 0.49325800000000 0.33537400000000 0.15788400000000
>>> Sb 0.84211600000000 0.50674200000000 0.66462600000000
>>> Sb 0.84211600000000 0.17749000000000 0.33537400000000
>>> Co 0.00000000000000 0.50000000000000 0.00000000000000
>>> Co 0.00000000000000 0.00000000000000 0.50000000000000
>>> Co 0.50000000000000 0.50000000000000 0.50000000000000
>>> Co 0.50000000000000 0.00000000000000 0.00000000000000
>>> End atoms_frac
>>>
>>> begin projections
>>> random
>>> end projections
>>>
>>> begin kpoint_path
>>> G 0.00000 0.00000 0.0000 H 0.5 -0.5 0.5
>>> H 0.5 -0.5 0.5 P 0.25 0.25 0.25
>>> P 0.25 0.25 0.25 N 0.0 0.5 0.0
>>> N 0.0 0.5 0.0 G 0.0 0.0 0.0
>>> end kpoint_path
>>>
>>>
>>> mp_grid = 4 4 4
>>>
>>> begin kpoints
>>> 0.00000000 0.00000000 0.00000000
>>> 0.00000000 0.00000000 0.25000000
>>> 0.00000000 0.00000000 0.50000000
>>> 0.00000000 0.00000000 0.75000000
>>> 0.00000000 0.25000000 0.00000000
>>> 0.00000000 0.25000000 0.25000000
>>> 0.00000000 0.25000000 0.50000000
>>> 0.00000000 0.25000000 0.75000000
>>> 0.00000000 0.50000000 0.00000000
>>> 0.00000000 0.50000000 0.25000000
>>> 0.00000000 0.50000000 0.50000000
>>> 0.00000000 0.50000000 0.75000000
>>> 0.00000000 0.75000000 0.00000000
>>> 0.00000000 0.75000000 0.25000000
>>> 0.00000000 0.75000000 0.50000000
>>> 0.00000000 0.75000000 0.75000000
>>> 0.25000000 0.00000000 0.00000000
>>> 0.25000000 0.00000000 0.25000000
>>> 0.25000000 0.00000000 0.50000000
>>> 0.25000000 0.00000000 0.75000000
>>> 0.25000000 0.25000000 0.00000000
>>> 0.25000000 0.25000000 0.25000000
>>> 0.25000000 0.25000000 0.50000000
>>> 0.25000000 0.25000000 0.75000000
>>> 0.25000000 0.50000000 0.00000000
>>> 0.25000000 0.50000000 0.25000000
>>> 0.25000000 0.50000000 0.50000000
>>> 0.25000000 0.50000000 0.75000000
>>> 0.25000000 0.75000000 0.00000000
>>> 0.25000000 0.75000000 0.25000000
>>> 0.25000000 0.75000000 0.50000000
>>> 0.25000000 0.75000000 0.75000000
>>> 0.50000000 0.00000000 0.00000000
>>> 0.50000000 0.00000000 0.25000000
>>> 0.50000000 0.00000000 0.50000000
>>> 0.50000000 0.00000000 0.75000000
>>> 0.50000000 0.25000000 0.00000000
>>> 0.50000000 0.25000000 0.25000000
>>> 0.50000000 0.25000000 0.50000000
>>> 0.50000000 0.25000000 0.75000000
>>> 0.50000000 0.50000000 0.00000000
>>> 0.50000000 0.50000000 0.25000000
>>> 0.50000000 0.50000000 0.50000000
>>> 0.50000000 0.50000000 0.75000000
>>> 0.50000000 0.75000000 0.00000000
>>> 0.50000000 0.75000000 0.25000000
>>> 0.50000000 0.75000000 0.50000000
>>> 0.50000000 0.75000000 0.75000000
>>> 0.75000000 0.00000000 0.00000000
>>> 0.75000000 0.00000000 0.25000000
>>> 0.75000000 0.00000000 0.50000000
>>> 0.75000000 0.00000000 0.75000000
>>> 0.75000000 0.25000000 0.00000000
>>> 0.75000000 0.25000000 0.25000000
>>> 0.75000000 0.25000000 0.50000000
>>> 0.75000000 0.25000000 0.75000000
>>> 0.75000000 0.50000000 0.00000000
>>> 0.75000000 0.50000000 0.25000000
>>> 0.75000000 0.50000000 0.50000000
>>> 0.75000000 0.50000000 0.75000000
>>> 0.75000000 0.75000000 0.00000000
>>> 0.75000000 0.75000000 0.25000000
>>> 0.75000000 0.75000000 0.50000000
>>> 0.75000000 0.75000000 0.75000000
>>> end kpoints
>>>
>>>
>>> _______________________________________________
>>> Wannier mailing list
>>> Wannier at quantum-espresso.org <mailto:Wannier at quantum-espresso.org>
>>> http://mailman.qe-forge.org/cgi-bin/mailman/listinfo/wannier
>>
>>
>>
>> <boltz.tar.gz><band.pdf>
>
>
>
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--
Giovanni Pizzi
Post-doctoral Research Scientist
EPFL STI IMX THEOS
MXC 340 (Bâtiment MXC)
Station 12
CH-1015 Lausanne (Switzerland)
Phone: +41 21 69 31124
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