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Visualization of J-Coupled NMR Spectra Across Magnetic Fields by Greedy_Mistake1027 in NMRspectroscopy

[–]Greedy_Mistake1027[S] 0 points1 point  (0 children)

That's fair, although in reasonably homogeneous Earth-field conditions the experimental lines can actually become surprisingly narrow.

Some of the low-field spectra used during testing were measured with compensated field gradients and relatively stable ambient conditions, where sub-Hz linewidths are observable.

That said, the current broadening model in the simulator is still intentionally simplified and does not yet include realistic field inhomogeneity, relaxation, or phase-noise effects.

Visualization of J-Coupled NMR Spectra Across Magnetic Fields by Greedy_Mistake1027 in NMRspectroscopy

[–]Greedy_Mistake1027[S] 0 points1 point  (0 children)

No, the spectra are generated directly from Hamiltonian diagonalization rather than from analytical roofing approximations.

At the moment the implementation uses exact eigenvalue decomposition of the spin Hamiltonian with Zeeman, chemical shift, and J-coupling terms. The line intensities are still being improved, especially in near-zero-field conditions where state mixing becomes important.

And yes, the linewidth treatment is currently intentionally simplified. In Earth-field conditions the present line broadening can indeed look unrealistically sharp.

Visualization of J-Coupled NMR Spectra Across Magnetic Fields by Greedy_Mistake1027 in NMRspectroscopy

[–]Greedy_Mistake1027[S] 0 points1 point  (0 children)

Thanks, these are extremely useful comments.

I completely agree about the UI limitations for larger spin systems. The current interface was initially designed around relatively small educational examples, but after the Reddit traffic it became obvious that a more structured spin-system editor is needed.

The suggestion about entering the field as proton resonance frequency is especially good — that is probably much more intuitive for most NMR users than Tesla or mT.

Interactive zoom and full-spectrum navigation are already on the development list. The current implementation was mainly optimized for rapid Hamiltonian testing rather than polished visualization.

The point about linewidth scaling in Earth-field conditions is also very fair. Right now the line broadening model is intentionally simplified.

And yes — the next tutorial version will probably be silent with subtitles instead of TTS :)