7.4.1.4.2. 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 or dimer_guess (combine two monomer .orb files of independently arbitrary charge/spin – see dimer_guess_orbA/orbB below)	independent atom orbfile huckel huckel_dft dimer_guess
dftpackage.dimer_guess_orbA		Path to monomer A’s own, already-converged .orb file – only read when initial_guess=dimer_guess. Monomer A’s atoms must be an exact internal-geometry match (bond lengths/angles, NOT absolute position – translation/rotation between the standalone monomer and its placement in the dimer is expected and fine) for the first N_A atoms of this calculation’s own molecule.
dftpackage.dimer_guess_orbB		Same as dimer_guess_orbA, for monomer B – expected to match this calculation’s own remaining atoms (after monomer A’s own N_A atoms).
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.force_uks_path	false	forcing UKS path	bool
dftpackage.xtpdft.compute_forces	false	Compute analytic ground-state DFT nuclear forces (RI, and hybrid-exchange for UKS) and store them in the orb (HDF5) file. Adds real cost to every converged SCF, so this is opt-in.	bool
dftpackage.xtpdft.cdft.enabled	false	Enable a CDFT charge constraint on this calculation	bool
dftpackage.xtpdft.cdft.indices		Indices of atoms in the constrained fragment (0-based), using the same range syntax already used for diabatization.xml’s own fragment indices, e.g. ‘1 3 13:17’
dftpackage.xtpdft.cdft.charge	0.0	Target charge on the fragment, RELATIVE to its neutral reference state (the sum of the fragment atoms’ own nuclear charges) – e.g. +1.0 means one electron REMOVED from the fragment (a cation), -1.0 means one electron ADDED (an anion). Converted internally to an absolute target electron count once, at setup time.	float
dftpackage.xtpdft.cdft.initial_lambda	0.0	Initial guess for the Lagrange multiplier lambda, used as the center of the outer loop’s own bisection bracket	float
dftpackage.xtpdft.cdft.population_tolerance	1e-4	Outer-loop convergence criterion: the CDFT calculation is considered converged once the achieved fragment population is within this many electrons of the target	float+
dftpackage.xtpdft.cdft.max_iterations	50	Maximum number of outer (Lagrange-multiplier, bisection) iterations – each one is a full, warm-started inner SCF	int+
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+
dftpackage.xtpdft.convergence.mixing_end	0.8	DIIS error below which mixing is disabled – independent of ADIIS_start (see ORCA’s own DampErr, kept independent of DIISStart for the same reason: difficult systems benefit from keeping mixing active well past the point where ADIIS/DIIS themselves start being tried, not exactly until that same point). Defaults to match ADIIS_start’s own default (0.8) for backward compatibility – existing configurations see identical behavior unless this is set explicitly.	float+
dftpackage.xtpdft.convergence.mixing_max	0.98	Ceiling mixing can adaptively ramp up toward as the SCF struggles (see consecutive ADIIS failures), rather than staying fixed at the base mixing value for an entire run. Matches ORCA’s own DampMax (default 0.98, confirmed directly from a real ORCA log’s own resolved SCF settings) – ORCA ramps its own damping factor from a base (DampFac, 0.7 by default) up to this ceiling only when actually needed, rather than paying the cost of heavy damping throughout.	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+
dftcoupling.output_tb	false	Output Tight-Binding Hamiltonian matrix	bool
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 `