|Molecule Types Asymmetric Tops
Note that only nuclei not explicitly simulated with nucleus
objects should be included in calculating the statistical
weights (eeWt and so
on). If all equivalent nuclei have been explicitly included,
then the statistical weights should be calculated as if there
were an additional pair of equivalent spin zero nuclei, which
will mean some mean weighs will be zero. A simple check for
correct operation is to compare the rotational structure with
and without the nuclei explicitly included, with the weights
calculated in the latter case including all nuclei. If the
linewidth is set somewhat larger than the width of the hyperfine
structure the spectra should appear identical.
For interactions between nuclei see Nuclear Spin - Nuclear Spin Coupling
|Nuclear spin. (Note that this setting should logically be at the molecule, rather than the state level. Changing a spin here will change the corresponding spins in any other states.)
|Set to indicate that this nucleus is equivalent to the
following nucleus. This is required for molecules with a
centre of symmetry, where nuclei not on the centre of
symmetry must occur as equivalent pairs. In these
circumstances all parameters are taken from the second of
the two nuclei, and the modified coupling scheme:
I12 = I1 + I2; F = J + I12is used. This setting can also be used for molecules without low symmetry (C1, Ci, Cs), in which case the alternate coupling scheme is used but the nuclei are not forced to be identical. Note that equivalent nuclei are not currently implemented for D2 and D2h symmetry.
|Maximum ΔJ to include to consider in evaluating matrix elements for this nucleus. Default is negative, which includes all possible matrix elements, but setting this to zero (or possibly 1) can give significantly faster calculations but may be less accurate, particularly for low J.
Note that where x, y and z axes are
referred to below, the mapping to a, b and c
axes is determined by the representation - see Symmetry and Axis Systems so that, for
example, CHIzz corresponds to χaa in a Ir
representation but χcc in a IIIr
|Nuclear spin - electron spin Fermi Contact interaction (I.S).
|Tzz = -(Txx+Tyy) component of Nuclear spin - electron spin dipole dipole interaction.
|Txx-Tyy component of Nuclear spin - electron spin dipole dipole interaction.
|ab component of Nuclear spin - electron spin dipole dipole interaction.
|ac component of Nuclear spin - electron spin dipole dipole interaction.
|bc component of Nuclear spin - electron spin dipole dipole interaction.
|zz component of Nuclear Quadrupole interaction.
|xx-yy component of Nuclear Quadrupole interaction.
|ab component of Nuclear Quadrupole interaction.
|ac component of Nuclear Quadrupole interaction.
|bc component of Nuclear Quadrupole interaction.
|aa component of Nuclear Spin - Rotation interaction.
|bb component of Nuclear Spin - Rotation interaction.
|cc component of Nuclear Spin - Rotation interaction.