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Linear Molecule Nucleus

If the parent molecule has nNuclei non zero, then each state will have nNuclei LinearNucleus objects. (In principle the Spin and AsNext properties should be set at the molecule level, but in fact have been implemented at the state level, and any change in these two properties is copied to all the states in the molecule.) The following coupling scheme is normally used:
F1 = J1 + I1; F2 = F1 + I2; ... F = Fn-1 + In
though at alternative scheme must be used for equivalent nuclei, as described under the AsNext setting.

Note that only nuclei not explicitly simulated with nucleus objects should be included in calculating the SymWt and AsymWt statistical weights. 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 AsymWt must be set to 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 the Nuclear Spin - Nuclear Spin Coupling.

Settings

Spin Nuclear spin.
AsNext 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 + I12
is used.
This setting can also be used for molecules without a centre of symmetry, in which case the alternate coupling scheme is used but the nuclei are not forced, or even required, to be identical.
MaxDJ 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.

Parameters

a Nuclear spin - orbit interaction, I.L.
b Nuclear spin - electron spin I.S. Note that b = bF - c/3.
c Nuclear spin - electron spin dipole dipole interaction diagonal in Lambda.
d Nuclear spin - electron spin dipole dipole interaction off diagonal in Lambda by 2.
eQq0 Nuclear quadrupole coupling constant diagonal in Lambda.
eQq2 Nuclear quadrupole coupling constant off diagonal in Lambda by 2.
cI Nuclear spin rotation, I.J. Note that I.N = I.(J-S) is sometimes used, which is equivalent to subtracting cI from b.
cIp cI' = Nuclear spin rotation, I.J off diagonal in Lambda by 2. Note that the quivalent operator involving N is equivalent to subtracting cIp from d.
aJ Centrifugal distortion of nuclear spin - orbit interaction (I.L). (Outline implementation - a more exact implementation can be obtained with a perturbation with Op = bF and Npower = 2)
bJ Centrifugal distortion of nuclear spin - electron spin (I.S). (Outline implementation - a more exact implementation can be obtained with a perturbation with Op = aL and Npower = 2).
cJ Centrifugal distortion of nuclear spin - electron spin dipole dipole interaction diagonal in Lambda. (Outline implementation)
dJ Centrifugal distortion of nuclear spin - electron spin dipole dipole interaction off diagonal in Lambda by 2. Note that the full implementation was added in 10.1.151, and the results from earlier versions will only be approximately consistent.
eQq0J Centrifugal distortion of nuclear quadrupole coupling constant diagonal in Lambda. (Outline implementation)
eQq2J Centrifugal distortion of nuclear quadrupole coupling constant off diagonal in Lambda by 2. (Outline implementation)