# TRANSPORT

References: Bruck2014

Specifies the parameters for transport, sets parameters for the OMEN code, see also https://nano-tcad.ee.ethz.ch. [Edit on GitHub]

Subsections

- BEYN
- CONTACT
- PEXSI
- PRINT

## Keywords

- COLZERO_THRESHOLD

- CONTACT_FILLING

- CSR_SCREENING

- CUTOUT

- DENSITY_MIXING

- ENERGY_INTERVAL

- EPS_DECAY

- EPS_EIGVAL_DEGEN

- EPS_FERMI

- EPS_LIMIT

- EPS_LIMIT_CC

- EPS_MU

- EPS_SINGULARITY_CURVATURES

- GPUS_PER_POINT

- INJECTION_METHOD

- LINEAR_SOLVER

- MATRIX_INVERSION_METHOD

- MIN_INTERVAL

- NUM_INTERVAL

- NUM_POLE

- N_KPOINTS

- N_POINTS_INV

- OBC_EQUILIBRIUM

- QT_FORMALISM

- REAL_AXIS_INTEGRATION_METHOD

- TASKS_PER_ENERGY_POINT

- TASKS_PER_POLE

- TEMPERATURE

- TRANSPORT_METHOD

## Keyword descriptions

COLZERO_THRESHOLD: real = 1.00000000E-012

  Usage: COLZERO_THRESHOLD <real>

  The smallest number that is not zero in the full diagonalization part. [Edit on GitHub]

CONTACT_FILLING: enum = BAND_STRUCTURE

  Valid values:

  - `BAND_STRUCTURE` Determine the Fermi levels from the band structure.

  - `DOS` Determine the Fermi levels from the density of states.

  Determination of the contact Fermi levels. Note that this keyword only works when the TRANSPORT_METHOD is specified as TRANSPORT. [Edit on GitHub]

CSR_SCREENING: logical = T

  Lone keyword: `T`

  Whether distance screening should be applied to improve sparsity of CSR matrices. [Edit on GitHub]

CUTOUT: integer[2] = 0 0

  Usage: CUTOUT <integer> <integer>

  The number of atoms at the beginning and the end of the structure where the density should not be changed. [Edit on GitHub]

DENSITY_MIXING: real = 1.00000000E+000

  Usage: DENSITY_MIXING <real>

  Mixing parameter for a density mixing in OMEN. [Edit on GitHub]

ENERGY_INTERVAL: real = 1.00000000E-003

  Usage: ENERGY_INTERVAL <real>

  Distance between energy points in eV. [Edit on GitHub]

EPS_DECAY: real = 1.00000000E-004

  Usage: EPS_DECAY <real>

  The smallest imaginary part that a decaying eigenvalue may have not to be considered as propagating. [Edit on GitHub]

EPS_EIGVAL_DEGEN: real = 1.00000000E-006

  Usage: EPS_EIGVAL_DEGEN <real>

  Filter for degenerate bands in the injection vector. [Edit on GitHub]

EPS_FERMI: real = 0.00000000E+000

  Usage: EPS_FERMI <real>

  Cutoff for the tail of the Fermi function. [Edit on GitHub]

EPS_LIMIT: real = 1.00000000E-004

  Usage: EPS_LIMIT <real>

  The smallest eigenvalue that is kept. [Edit on GitHub]

EPS_LIMIT_CC: real = 1.00000000E-006

  Usage: EPS_LIMIT_CC <real>

  The smallest eigenvalue that is kept on the complex contour. [Edit on GitHub]

EPS_MU: real = 1.00000000E-006

  Usage: EPS_MU <real>

  Accuracy to which the Fermi level should be determined. [Edit on GitHub]

EPS_SINGULARITY_CURVATURES: real = 1.00000000E-012

  Usage: EPS_SINGULARITY_CURVATURES <real>

  Filter for degenerate bands in the bandstructure. [Edit on GitHub]

GPUS_PER_POINT: integer = 2

  Usage: GPUS_PER_POINT <integer>

  Number of GPUs per energy point for SplitSolve. Needs to be a power of two [Edit on GitHub]

INJECTION_METHOD: enum = BEYN

  Usage: INJECTION_METHOD <method>

  Valid values:

  - `EVP` Full eigenvalue solver.

  - `BEYN` Beyn eigenvalue solver.

  Method to solve the eigenvalue problem for the open boundary conditions. [Edit on GitHub]

LINEAR_SOLVER: enum = FULL

  Usage: LINEAR_SOLVER <solver>

  Valid values:

  - `SPLITSOLVE`

  - `SUPERLU`

  - `MUMPS`

  - `FULL`

  - `BANDED`

  - `PARDISO`

  - `UMFPACK`

  Preferred solver for solving the linear system of equations. [Edit on GitHub]

MATRIX_INVERSION_METHOD: enum = FULL

  Usage: MATRIX_INVERSION_METHOD <solver>

  Valid values:

  - `FULL`

  - `PEXSI`

  - `PARDISO`

  - `RGF`

  Preferred matrix inversion method. [Edit on GitHub]

MIN_INTERVAL: real = 1.00000000E-004

  Usage: MIN_INTERVAL <real>

  Smallest enery distance in energy vector. [Edit on GitHub]

NUM_INTERVAL: integer = 10

  Usage: NUM_INTERVAL <integer>

  Max number of energy points per small interval. [Edit on GitHub]

NUM_POLE: integer = 64

  Usage: NUM_POLE <integer>

  The number of terms in the PEXSI’s pole expansion method. [Edit on GitHub]

N_KPOINTS: integer = 64

  Usage: N_KPOINTS <integer>

  The number of k points for determination of the singularities. [Edit on GitHub]

N_POINTS_INV: integer = 64

  Usage: N_POINTS_INV <integer>

  Number of integration points for the sigma solver on the complex contour. [Edit on GitHub]

OBC_EQUILIBRIUM: logical = F

  Lone keyword: `T`

  Compute the equilibrium density with open boundary conditions. [Edit on GitHub]

QT_FORMALISM: enum = QTBM

  Usage: QT_FORMALISM <method>

  Valid values:

  - `NEGF` The non-equilibrium Green’s function formalism.

  - `QTBM` The quantum transmitting boundary method / wave-function formalism.

  Preferred quantum transport formalism to compute the current and density. [Edit on GitHub]

REAL_AXIS_INTEGRATION_METHOD: enum = GAUSS_CHEBYSHEV

  Usage: REAL_AXIS_INTEGRATION_METHOD <method>

  Valid values:

  - `GAUSS_CHEBYSHEV` Gauss-Chebyshev integration between singularity points.

  - `TRAPEZOIDAL_RULE` Trapezoidal rule on the total range.

  - `READ` Read integration points from a file (named E.dat).

  Integration method for the real axis. [Edit on GitHub]

TASKS_PER_ENERGY_POINT: integer = 1

  Usage: TASKS_PER_ENERGY_POINT <integer>

  Number of tasks per energy point. The value should be a divisor of the total number of MPI ranks. [Edit on GitHub]

TASKS_PER_POLE: integer = 1

  Usage: TASKS_PER_POLE <integer>

  Number of tasks per pole in the pole expansion method. The value should be a divisor of the total number of MPI ranks. [Edit on GitHub]

TEMPERATURE: real = 3.00000000E+002 [K]

  Usage: TEMPERATURE [K] 300.0

  Temperature. [Edit on GitHub]

TRANSPORT_METHOD: enum = TRANSPORT

  Usage: TRANSPORT_METHOD <method>

  Valid values:

  - `TRANSPORT` self-consistent CP2K and OMEN transport calculations

  - `LOCAL_SCF` CP2K valence Hamiltonian + OMEN self-consistent calculations on conduction electrons

  - `TRANSMISSION` self-consistent transmission calculations without applied bias voltage

  Preferred method for transport calculations. [Edit on GitHub]