In DALTON the nuclear spin-rotation constants are calculated using rotational orbitals, giving an improved basis set convergence [44]. We use the expression for the spin-rotation constant where the paramagnetic term is evaluated around the center of mass, and thus will only solve three response equations at the most.
An input requesting the calculation of spin-rotation constants will look like
**DALTON INPUT
.RUN PROPERTIES
**WAVE FUNCTIONS
.HF
**PROPERTIES
.SPIN-R
.ISOTOP
3
2 1 1
*END OF INPUT
As the nuclear spin-rotation constants depend on the isotopic substitution of the molecule, both through the nuclear magnetic moments and through the center of mass, the isotopic constitution need to be specified if this is different from the most abundant isotopic constitution. Note that some of the most common isotopes do not have a magnetic moment.
We note that in the current release of DALTON , nuclear spin-rotation
constants can not be calculated employing symmetry-dependent
nuclei. Thus for a molecule like N 
, the symmetry plane
perpendicular to the molecular bond will have to be removed during the
calculation.