Changes

See Figure 1 and 10 in the reference.:  Palmer, A.G. & Massi, F. (2006). Characterization of the dynamics of biomacromolecules using rotating-frame spin relaxation NMR spectroscopy. Chem. Rev. 106, 1700-1719 [http* {{#lst://dx.doi.org/10.1021/cr04042875 DOI]Citations|PalmerMassi06}}

These values reflects offset frequencies to the carrier frequency, and in relax is noted as '''"Spin-lock offset, the frequency of of the rf field" ''' : $\mathbf{\omega_{rf:omegarf}}$.

Relax needs input for {{:omegarf}} in ppm, and during calculations converts to the rad/s, with the following function callscall.

If you need to convert to ppm from Hz values, consider during this in your relax script. <br>If for example you have recorded at a 800 MHz spectrometer, you could find the Carrier position for ¹⁵N (Value of yCar in NMRPipe scripts). If yCAR = 118.078 ppm, then<source lang="python">from lib.nmr import frequency_to_Hz, frequency_to_ppm # Spectrometer frequencysfrq =799.7773991 # MHz# Carrier positionyCAR = 118.078 # ppm  # We take the absolute value, since the gyromagnetic ratio of N15 is negative.yCAR_Hz = abs(frequency_to_Hz(frq= spin lock field yCAR, B0=sfrq*1E6, isotope='15N'))# We add the offset (deltadof2 in varian pulse sequences) in Hz, and from 0 to 10.000yCar_offset_Hz =yCAR_Hz + float(deltadof2)# The spin lock field strength convert back from Hz to ppm. Again absolute value, because of the gyromagnetic ratio of N15 is noted negative.yCar_offset_ppm = abs(frequency_to_ppm(frq=yCar_offset_Hz, B0=sfrq*1E6, isotope='15N')) relax_disp.spin_lock_offset(spectrum_id=sp_id, offset=yCar_offset_ppm)</source>   '''$\nu_1$Offset in the literature'''<br> The offset is in the literature noted as Ω_S, where Ω_S is the (Ex. ¹⁵N) resonance offset from the spin-lock carrier. Note that Ω<brsub>S</sub>is dependent of the [[wikipedia:Chemical_shift | chemical shifts]] δ in ppm for the nuclei of interest. The [[wikipedia:Chemical_shift | Chemical Shifts]] $\delta$ δ in ppm for nuclei of interest (ex. $^{^15}$N and which have been loaded in with relax function [http://www.nmr-relax.com/manual/chemical_shift_read.html chemical_shift_read] from a [http://www.nmr-relax.com/manual/spectrum_read_intensities.html peak list formatted file]) is first converted to to the rad/s with the following function calls. <math>\bar{\omega}_{S,i} = 2\pi \cdot \delta_{S,i} \cdot B_0 \cdot \frac{\gamma_{^{15}N}}{\gamma_{^{1}H}}</math> 

 Then $\Delta \omega_S$ <span style="text-decoration: overline">Ω_S</span> is calculated with: $\Delta \omega_{<span style="text-decoration: overline">Ω_S,i</span> = <span style="text-decoration: overline">Ω_S,i</span> - {{:omegarf}} , where <span style= \delta_{"text-decoration: overline">Ω</span> is the population averaged Larmor frequency of the spin and comes from the conversion of the [[wikipedia:Chemical_shift | Chemical Shifts]] δ_S,i} to frequency <span style="text- \Omega_S$decoration: overline">Ω_S,i</span>.

=== spin lock field ===The spin lock field strength is noted {{:nu1}}, and relax requires these to be provided in unit of '''rad/s'''.<br> The trouble spin lock field strength is converted to rad/s, with the following function call. <math>\omega_{S,1} =2\pi \cdot \nu_{S,1}</math> <source lang="python">omega1 =point * 2.0 * pi</source> The trouble Then the Rotating frame tilt angle θ iscalculated.

At page 1708 <source lang="python">if Delta_omega == 0.0: theta[ei][si][mi][oi].append(pi / 2.0)# Calculate the theta angle describing the tilted rotating frame relative to the laboratory.# If Delta_omega is states negative, there follow the symmetry of atan, that w_1S atan(-x) = - atan(x).# Then it should be: theta = w_1 and w_eS pi + atan(-x) = w_epi - atan(x) = pi - abs(atan( +/- x))elif omega1 / Delta_omega > 0 : theta[ei][si][mi][oi].append(atan(omega1 / Delta_omega))And in pulse sequence it states thatelse: theta[ei][si][mi][oi].append(pi + atan(omega1 / Delta_omega))</source>

[[Category:Relaxation_dispersionRelaxation dispersion analysis]]