[Wannier] confusion on conductivity tensor calculation
Jun Liu
jun.physics at gmail.com
Wed May 31 18:42:13 CEST 2017
Dear wannier users,
I would like to ask whether the following input for conductivity tensor
calculation looks ok.
num_bands = 128 ! set to NBANDS by VASP
num_wann = 88
begin projections
Mo:d ! 20
Te:p ! 24
end projections
###########BoltzWann ############
boltzwann = true
kmesh = 400 400 400
boltz_relax_time = 0.001
boltz_mu_min = 7.95123782 #ef-def
boltz_mu_max = 8.35123782
boltz_mu_step = 0.04
boltz_temp_min = 2
boltz_temp_max = 10
boltz_temp_step = 2
boltz_tdf_energy_step=0.01
boltz_tdf_smr_fixed_en_width = 0.01
boltz_tdf_smr_type = gauss
boltz_calc_also_dos = true
boltz_dos_energy_min = 5.0
boltz_dos_energy_max = 15.0
boltz_dos_energy_step = 0.01
#################################
write_hr = .true.
# Bandstructure
restart = plot
bands_plot = true
begin kpoint_path
....
end kpoint_path
bands_num_points 100 # bands_plot_format gnuplot
spinors = .true.
begin unit_cell_cart
3.4716802 0.0000000 0.0000000 /*this and the next line
changes*/
0.0000000 6.3666750 0.0000000 /*accordingly for different
cases*/
0.0000000 0.0000000 13.8452386
end unit_cell_cart
begin atoms_cart
...
end atoms_cart
mp_grid = 12 6 3 /*this line differs from each case*/
begin kpoints
...
end kpoints
This input returns reasonable result (in that the conductivity tensor is
nearly diagonal for orthorhombic structure). But if I compare results
across different cases, they differ too much under as small as 0.5% lattice
constant change. More details are given below.
I tried to calculate the conductivity tensor with postw90.x with version
2.1. I tried it on three cases related with slight elongation along a or b
directions defining an orthorhombic structure on the original lattice. The
resulting conductivity tensor differs by nearly 100% for a 0.5% lattice
constant change, which cannot be right. To give you some numbers, the
following shows different sigma_x,x scanned under different chemical
potentials for different lattice structures, (other components of sigma are
suppressed for brevity but the whole sigma matrix does show a diagonal
feature expected for an orthorhombic structure.)
For the base structure (a,b,c)
mu T sigma_x,x
7.963542580 2.000000000 0.4228380355E-05
7.963542580 4.000000000 0.6146815602E-01
7.963542580 6.000000000 1.261398051
7.963542580 8.000000000 5.250207712
7.963542580 10.00000000 11.71261179
For the elongated structure along a by 0.5%
mu T sigma_x,x
7.962242580 2.000000000 0.5201871790E-03
7.962242580 4.000000000 0.6688530829
7.962242580 6.000000000 6.051666588
7.962242580 8.000000000 16.35207686
7.962242580 10.00000000 27.52636769
For the elongated structure along b by 0.5%
mu T sigma_x,x
7.951237820 2.000000000 332.9039665 <%28332%29%20903-9665>
7.951237820 4.000000000 363.9745377
7.951237820 6.000000000 287.1196636
7.951237820 8.000000000 228.9187157 <%28228%29%20918-7157>
7.951237820 10.00000000 188.4869745
Any idea on how to check the calculation? Thanks all very much for your
insightful help!
Sincerely,
Jun
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