[Pw_forum] transmission calculation

[Manoj Srivastava]

Dear PWSCF users and developers,
 I have been trying to do the conductance calculation for the twin
boundary of Cu. I compared my results with previously done calculations
and for most K points the transmission coefficients match up very well.
But there are some k points that I get transmission coefficients more than
1! This is not reasonable, as the maximum value of transmission
coefficient could be 1.I am getting 1.000345, and similar for other k
points. Do you think transmission coefficients being more than 1 is just
numerical error of the code or there is something wrong with my input
file? Attached is the input file for lead and scatterign region -

SCF for the LEFT lead-
&control
    calculation='scf'
    pseudo_dir = '/home/manoj/espresso-4.0.1/pseudo',
    outdir='./',
    prefix='lcu',
 /
 &system
    ibrav =0,
    celldm(1)=4.82,
    nat= 3,
    ntyp= 1,
    ecutwfc =150.0,
    occupations='smearing',
    smearing='gaussian',
    degauss=0.02,
    ecutrho=500
 /
 &electrons
    conv_thr = 1.0e-8
    mixing_beta=0.7
 /
ATOMIC_SPECIES
 Cu 63.55  Cu.pz-d-rrkjus.UPF
ATOMIC_POSITIONS
  Cu  0.0   0.0                0.0
  Cu -0.5   0.288675134        0.81649658
  Cu -1.0   0.577350269        1.632993162

K_POINTS (automatic)
6 6 8 1 1 1
CELL_PARAMETERS {hexagonal}
 1.0   0.0    0.0
-0.5   0.8660254037844386 0.0
 0.0   0.0     2.449489743
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
SCF for the RIGHT lead-
&control
    calculation='scf'
    pseudo_dir = '/home/manoj/espresso-4.0.1/pseudo',
    outdir='./',
    prefix='rcu',
 /
 &system
    ibrav =0,
    celldm(1)=4.82,
    nat= 3,
    ntyp= 1,
    ecutwfc =150.0,
    occupations='smearing',
    smearing='gaussian',
    degauss=0.02,
    ecutrho=500
 /
 &electrons
    conv_thr = 1.0e-8
    mixing_beta=0.7
 /
ATOMIC_SPECIES
 Cu 63.55  Cu.pz-d-rrkjus.UPF
ATOMIC_POSITIONS
  Cu 0.0   0.0                0.0
  Cu 0.5  -0.288675134        0.81649658
  Cu 1.0  -0.577350269        1.632993162

K_POINTS (automatic)
6 6 8 1 1 1
CELL_PARAMETERS {hexagonal}
 1.0  0.0    0.0
-0.5  0.8660254037844386  0.0
 0.0   0.0     2.449489743

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
SCF for SCATTERING region-
&control
    calculation='scf'
    pseudo_dir = '/home/manoj/espresso-4.0.1/pseudo',
    outdir='./',
    prefix='scu',
 /
 &system
    ibrav =0,
    celldm(1)=4.82,
    nat= 12,
    ntyp= 1,
    ecutwfc =150.0,
    occupations='smearing',
    smearing='gaussian',
    degauss=0.02,
    ecutrho=500
 /
 &electrons
    conv_thr = 1.0e-8
    mixing_beta=0.7
/
ATOMIC_SPECIES
 Cu 63.55  Cu.pz-d-rrkjus.UPF
ATOMIC_POSITIONS
  Cu  0.0   0.0         0.0
  Cu -0.5   0.288675134 0.816496581
  Cu -1.0   0.577350269 1.632993162
  Cu -0.5   0.288675134 2.449489743
  Cu  0.0   0.0         3.265986324
  Cu  0.5  -0.288675134 4.082482905
  Cu  1.0  -0.577350269 4.898979486
  Cu  1.5  -0.866025404 5.715476066
  Cu  2.0  -1.154700538 6.531972647
  Cu  1.5  -0.866025404 7.348469228
  Cu  1.0  -0.577350269 8.164965809
  Cu  0.5  -0.288675134 8.981462390

K_POINTS (automatic)
6 6 4 1 1 1
CELL_PARAMETERS {hexagonal}
 1.0   0.0         0.0
-0.5   0.866025403 0.0
 0.0   0.0         9.797958971

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
input file for conductance part-

&inputcond
    outdir='./'
    prefixs='scu'
    prefixl='lcu'
    prefixr='rcu'
    tran_file ='trans.twin'
    ikind=2
    ecut2d=200
    energy0=0.0
    denergy=0.0
    ewind=101.d0
    epsproj=1.d-6
    nz1=25
    bds=3.265986324

 /
  6
  0.5000000     -0.5000000               1
  4.2584095E-17  0.5000000               1
  0.250000000    0.0000000               1
  0.1666667      0.1666667               1
 -1.2775231E-16 -0.2500000               1
  0.2500000     -0.2500001               1
1
0.0


Regards, 
Manoj Srivastava 
University of Florida, 
Gainesville, FL