The necessary input for a finite-field calculation is given in the **INTEGRALS and **WAVE FUNCTIONS input modules. A typical input file for an finite field SCF calculation of the magnetizability of a molecule will be:
**DALTON INPUT .RUN PROPERTIES **INTEGRALS .DIPLEN **WAVE FUNCTIONS .HARTREE-FOCK *HAMILTONIAN .FIELD 0.003 XDIPLEN **PROPERTIES .MAGNET *END OF INPUT
In the **INTEGRALS
input module we request the evaluation of dipole
length integrals, as these correspond to
the electric dipole operator ,
and will be used when in SIRIUS for evaluating the interactions between the
electric dipole and the external electric field. This is achieved in
the *HAMILTONIAN
input module, where the presence of an external
electric field is signaled by the keyword .FIELD
. On the next line, the
strength of the electric field (in atomic units) is given, and on the following
line we give the direction of the applied electric field
(XDIPLEN
, YDIPLEN
, or ZDIPLEN
). Several fields may
of course be applied at the same time.