[Pw_forum] Transmission from PWCOND

[Vladislav Borisov]

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