what is the best available (free) computational tool for predicting NMR spectra? As I mentioned, I understand that predictions are imperfect. What software, if any, are widely used by practicing chemists for NMR simulation? What is the best reference to read about such software, including the heuristics and algorithms it uses to simulate spectra? Is Vespa and/or PyGamma state of the art? The NMR DB site is nice, but I'd very much prefer an interface that is amenable to scripting, and where structures could be supplied computationally rather than via a GUI interface.
(I'm a mass spectrometrist and biochemical engineer with little training in NMR methods.