[Pw_forum] Transmission from PWCOND

[nicvok]

The spin-contributions are calculated separately (T_j) and at the end  
all contributions are summed up
and are weighted with their corresponding Brillouin-zone weight (wkpt,  
trans_tot) in do_cond.f90 -> T_tot.
So I guess, it is either something wrong with the BZ-weighting (see  
summary_tran.f90 and do_cond.f90) or with the
summation over iofspin (transmit.f90). You used nspin=2 in scf-calc  
and now separate the transmission by
spin-channel, so I guess it's the latter.
You should do a check for a simple (T_tot=2) non-metallic metal (eg.  
copper) and ferromagnetic metal (bcc iron) with both
nspin=1&2.

You said the results of the 5.01 version and the CVS version differ.  
Which CVS/SVN Revision are you using?


-------------------------------------------------------------
Nicki Frank Hinsche, Dr. rer. nat.
Institute of physics - Theoretical physics,
Martin-Luther-University Halle-Wittenberg,
Von-Seckendorff-Platz 1, Room 1.07
D-06120 Halle/Saale, Germany
Tel.: ++49 345 5525460
-------------------------------------------------------------


Am 12.06.2014 um 12:00 schrieb pw_forum-request at pwscf.org:

> Date: Thu, 12 Jun 2014 08:38:31 +0200
> From: Vladislav Borisov <vborisov at mpi-halle.mpg.de>
> Subject: [Pw_forum] Transmission from PWCOND
> To: pw_forum at pwscf.org
> Message-ID: <e99409ee66e329da56c59effeb2a7df3 at mpi-halle.mpg.de>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> Dear all,
>
> I calculate the spin-polarized transmission for a tunnel junction
> using the PWCOND code. The calculation is performed for each k-point
> in the irreducible part of the Brillouin Zone separately.
> At the end of each output file one sees the contributions to the
> transmission from different propagating states (an example is shown
> below for the 5.0.1 version of the code).
>
> ************************************************************
> The input for PWCOND:
>
>  &inputcond
>    outdir       = '/scratch/vborisov/tmp/test/',
>    prefixl      = 'lead',
>    prefixs      = 'scat',
>    tran_file    = 'T-k1.Ef'
>    ikind        = 1,
>    iofspin      = 1,
>    energy0      = 0.00d0,
>    denergy      = -0.01d0,
>    ewind        = 2.d0,
>    epsproj      = 1.d-7,
>    delgep       = 1.d-7,
>    cutplot      = 3.d0,
>    nz1          = 22,
>    bds          = 9.667070904
>  /
>    1
>    0.00347222  0.00694445   1
>    1
>
>
> A part of the output:
>
> ---  E-Ef =    0.0000000  k =    0.0034722   0.0069444
> ---  ie =          1  ik =          1
>  Nchannels of the left tip =            1
>  Right moving states:
>    k1(2pi/a)   k2(2pi/a)   E-Ef (eV)
>   -0.3924556   0.0000000   0.0000000
>  Left moving states:
>    k1(2pi/a)   k2(2pi/a)   E-Ef (eV)
>    0.3924556   0.0000000   0.0000000
>
>  to transmit
>  Band j to band i transmissions and reflections:
>     j         i     |T_ij|^2    |R_ij|^2
>
>     1 -->     1     0.00014     0.99986
>    Total T_j, R_j =    0.00014  0.99986
>
>           E-Ef(ev), T =    0.0000000   0.0001402
>  Eigenchannel decomposition:
> #    1  0.00000  0.00014
>                       1.00000
>    T_tot     0.00000      0.28041E-03
>
> ************************************************************
>
> From this output, one would conclude that the transmission for
> this k-point equals 0.1402E-03. However, after this result comes
> also the eigenchannel decomposition and the T_tot value, which
> is twice as large and equals 0.28041E-03. The same behavior is
> observed for every other k-point. However, this discrepancy
> does not appear for the CVS version of the code.
>
> Where does this factor of 2 come from in the older version?
> Do the values of T_tot in these two versions always differ
> by the same factor of 2?
>
> I would very much appreciate any assistance with this problem.
>
>
> With kind regards,
> Vladislav Borisov
>
> Max Planck Institute of Microstructure Physics
> Weinberg 2, 06120, Halle (Saale), Germany
> Tel No: +49 345 5525448
> Fax No: +49 345 5525446
> Email: vborisov at mpi-halle.mpg.de


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