# 6.4.1.4.2. 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.

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 `