Quadrupolar Sideband Manifold

Quadrupolar sideband manifold simulation (spin 3/2 nucleus)

*******   Full sideband manifold      *********
****** The System *****************************
spectrometer(MHz)  500
spinning_freq(kHz) 10
channels           X(200 3/2)
nuclei             X
atomic_coords      *
cs_isotropic       *
csa_parameters     *
j_coupling         *
quadrupole         1 1000 0.25 0 0 0
dip_switchboard    *
csa_switchboard    *
exchange_nuclei    *
bond_len_nuclei    *
bond_ang_nuclei    *
tors_ang_nuclei    *
groups_nuclei      *
******* Pulse Sequence ************************
timing(usec)      (0)128
power(kHz)         0
phase(deg)         0
freq_offs(kHz)     0
****** Variables *******************************
******* Options ********************************
rho0               I1x
observables        I1p
EulerAngles        lebind65o
n_gamma            128
line_broaden(Hz)   *
zerofill           *
FFT_dimensions     1
options            -re -sz7 -fft1 -ws
-- This computes the intensities of the spinning sidebands.
The centerband (which is very intense) is "erased" in the Variables
section. This, of course, is not necessary, but illustrates possible
uses of the pre- and post-processing variables).
-- -sz7 option sets the number of frequency bins for collecting the
spectral intensities during the g-COMPUTE algorithm to 128. The spacing
between the centers of the bins is made to coincide with the spinning
frequency by choosing the dwell time equal to the 1/128-th of the rotor
period, which makes the spectral width equal to 128 spinning frequencies.
With this choice, each sideband, although broadened by the the 2nd-order
quadruplar interaction, is collected in just one bin. The total intensity
collected in that bin (i.e. the intensity of the point in the spectrum on
the output) then reflects the total sideband intensity over all orientations
in the powder.
-- Since the 2nd-order quadruplar interactions, although present in the
Hamiltonian, do not affect the total intensities of the sidebands, exactly
the same spectrum can be obtained with the -quad1 option.
-- The -ws option is specified to disable the interpolation of the spectal
frequencies (as functions of the orientation), which is useless in this case
since the frequencies are made orientation-independent by the way they are
binned. Enabling interpolation would produce the same result, but it would
take a bit longer to compute.
-- The spectum on the output is obtained by first computing the FID from the
binned spectrum produced by the g-COMPUTE algorithm (by computing the inverse
FT of that spectrum), which is then Fourier transformed back again. The -fft1
option ensures that the first point of the FID is not modified, so that the
spectum on the output coincides with the original binned spectrum.
-- This kind of input file is easily remade into a sideband fitting task
(see csa-sb-fitting example).