
coupling
********
Compute the electronic couplings from log and orbital files.
The following table contains the defaults input options for the calculator, The default `OPTIONAL` means this option is switched off, if no input is given. 
`REQUIRED` arguments have to be specified, otherwise an error is thrown.

.. list-table::
   :header-rows: 1
   :widths: 30 20 15 15
   :align: center

   * - Property Name
     - Default Value
     - Description
     - Valid Input
   * - job_name
     - system
     - | Input file name without extension, also used for intermediate
       | files
     - 
   * - dftpackage.name
     - xtp
     - Name of the DFT package
     - | xtp
       | orca
   * - dftpackage.charge
     - 0
     - Molecular charge
     - int
   * - dftpackage.spin
     - 1
     - Molecular multiplicity
     - int+
   * - dftpackage.basisset
     - def2-tzvp
     - Basis set for MOs
     - 
   * - dftpackage.auxbasisset
     - OPTIONAL
     - Auxiliary basis set for RI
     - 
   * - dftpackage.externalfield
     - OPTIONAL
     - Field given in x y z components
     - 
   * - dftpackage.executable
     - OPTIONAL
     - Path to executable for dftpackage
     - 
   * - dftpackage.ecp
     - OPTIONAL
     - Effective Core Potentials for DFT Calculations
     - 
   * - dftpackage.optimize
     - false
     - Perform a molecular geometry optimization
     - bool
   * - dftpackage.functional
     - XC_HYB_GGA_XC_PBEH
     - | Exchange correlation functional used. You can also specify
       | an exchange and a correlation functional
     - 
   * - dftpackage.scratch
     - /tmp/qmpackage
     - path to the scratch folder
     - 
   * - dftpackage.polarization
     - false
     - Calculate polarisation
     - bool
   * - dftpackage.dipole_spacing
     - 0.1
     - Spacing for splitting multipoles into charges
     - float+
   * - dftpackage.temporary_file
     - temp
     - Filename for temporary files without extension
     - 
   * - dftpackage.convergence_tightness
     - tight
     - How accurate the dft self-consistency has to be
     - | low
       | normal
       | tight
       | verytight
   * - dftpackage.cleanup
     - 
     - | files to remove after the calculation. Specify the fileextensions
       | 
     - 
   * - dftpackage.initial_guess
     - atom
     - | Method to use to make initial guess, independent(electrons)
       | or atom(densities) or previous calculation keyword orbfile
     - | independent
       | atom
       | orbfile
   * - dftpackage.orca
     - 
     - | orca specific keywords can be added here, where the xml
       | tag corresponds to the option and the value to the option's
       | value
     - 
   * - dftpackage.xtpdft.dft_in_dft.activeatoms
     - 
     - Indices of atoms in active region
     - 
   * - dftpackage.xtpdft.dft_in_dft.threshold
     - 0.4
     - | Mulliken population above which orbital is considered
       | in the active region
     - 
   * - dftpackage.xtpdft.dft_in_dft.levelshift
     - 10000.0
     - Levelshift energy for the projection operator
     - 
   * - dftpackage.xtpdft.dft_in_dft.truncate_basis
     - false
     - Truncate the basis-set to active atoms only
     - bool
   * - dftpackage.xtpdft.dft_in_dft.truncation_threshold
     - 1e-4
     - Threshold to convert an inactive atom to a border atom
     - float+
   * - dftpackage.xtpdft.screening_eps
     - 1e-9
     - screening eps
     - float+
   * - dftpackage.xtpdft.fock_matrix_reset
     - 5
     - how often the fock matrix is reset
     - int+
   * - dftpackage.xtpdft.integration_grid
     - medium
     - vxc grid quality
     - | xcoarse
       | coarse
       | medium
       | fine
       | xfine
   * - dftpackage.xtpdft.convergence.energy
     - 1E-7
     - DeltaE at which calculation is converged
     - float+
   * - dftpackage.xtpdft.convergence.method
     - DIIS
     - Main method to use for convergence accelertation
     - | DIIS
       | mixing
   * - dftpackage.xtpdft.convergence.DIIS_start
     - 0.002
     - DIIS error at which DIIS takes over
     - float+
   * - dftpackage.xtpdft.convergence.ADIIS_start
     - 0.8
     - DIIS error at which ADIIS takes over
     - float+
   * - dftpackage.xtpdft.convergence.DIIS_length
     - 20
     - old hamiltonians to keep in history
     - int+
   * - dftpackage.xtpdft.convergence.DIIS_maxout
     - false
     - | if true remove the maximum element in the history if DIIS_length
       | is exceeded.Otherwise, the oldest element is removed.
     - bool
   * - dftpackage.xtpdft.convergence.levelshift
     - 0.0
     - levelshift to apply to hamiltonian 
     - float+
   * - dftpackage.xtpdft.convergence.levelshift_end
     - 0.2
     - DIIS error at levelshifting is disabled
     - float+
   * - dftpackage.xtpdft.convergence.max_iterations
     - 100
     - max iterations to use
     - int+
   * - dftpackage.xtpdft.convergence.error
     - 1e-7
     - convergence error
     - float+
   * - dftpackage.xtpdft.convergence.mixing
     - 0.7
     - mixing parameter for linear mixing of density matrices
     - float+
   * - dftcoupling.degeneracy
     - 0.0
     - Criterium for the degeneracy of two levels
     - float+
   * - dftcoupling.levA
     - 1
     - | Output HOMO, ..., HOMO-levels; LUMO, ..., LUMO+levels,
       | molecule A
     - int+
   * - dftcoupling.levB
     - 1
     - | Output HOMO, ..., HOMO-levels; LUMO, ..., LUMO+levels,
       | molecule B
     - int+
   * - moleculeA.log
     - A.log
     - Log file of molecule A
     - 
   * - moleculeA.orbitals
     - A.orb
     - Orbitals file
     - 
   * - moleculeB.log
     - B.log
     - Log file of molecule B
     - 
   * - moleculeB.orbitals
     - B.orb
     - Orbitals file
     - 
   * - dimerAB.log
     - AB.log
     - Log file of dimer AB
     - 
   * - dimerAB.orbitals
     - AB.orb
     - Orbitals file
     - 
.. note::
   An *xml* file containing the defaults for the `coupling` calculator can be created via `-p coupling -o FILENAME` command line options `
