Hypertext Dalton 2.0 manual - Theoretical Chemistry, KTH

CHAPTER 25.
HF, SOPPA, AND MCSCF MOLECULAR PROPERTIES, ABACUS241
By definition the gauge origin of the spin-rotation constant is to be the center of mass
of the molecule, and although the gauge origin can be changed through the keywords
.NOCMC and .GAUGEO, this is not recommended, and may give erroneous results.
In the current implementation, symmetry dependent nuclei cannot be used during the
calculation of spin-rotation constants.
.SPIN-S Invokes the calculation of indirect nuclear spin-spin coupling constants. By default
all spin-spin couplings between nuclei with naturally occuring isotopes with abundance
more than 1% and non-zero spin will be calculated, as well as all the different contributions
(Fermi contact, dia- and paramagnetic spin-orbit and spin-dipole). The
implementation is described in Ref. [61].
As this is a very time consuming property, it is recommended to consult the chapter
describing the calculation of NMR-parameters (Ch. 10). The main control of which
contributions and which nuclei to calculate spin-spin couplings between is done in the
*SPIN-S module.
.VCD Invokes the calculation of Vibrational Circular Dichroism (VCD) according to the
implementation described in Ref. [78]. By default this is done using London orbitals
in order to ensure fast basis set convergence as shown in Ref. [83]. The use of London
orbitals can be disabled by the keyword .NOLOND.
Furthermore, the natural connection (Ref. [64, 82]) is default in order to ensure numerically
stable results. The natural connection can be turned off by the keyword
.NODIFC in which case the symmetric connection will be used.
In the current implementation, the keyword .NOCMC will be set true in calculations of
Vibrational Circular Dichroism, that is, the coordinate system origin will be used as
gauge origin. Changing this default value will give incorrect results for VCD.
Note that in the current release, VCD is not implemented for Density functional theory
calculations, and the program will stop if VCD is requested for a DFT calculation.
.VIBANA Invokes a vibrational analysis in the current geometry. This will generate the vibrational
frequencies in the current point. If combined with .DIPGRA the IR intensities
will be calculated as well.
.VROA Invokes the calculation of Vibrational Raman Optical Activity, as described in
Ref. [42]. This property needs a lot of settings in order to perform correctly, and
the reader is therefore refered to Section 11.4, where the calculation of this property
is described in more detail.