Dear cryoSPARC team
We’ve been enjoyed the helical refinement function in cryoSPARC. But recently I noticed a strange behavior of the Helical refinement from two unrelated helical objects. They are both pretty large in diameter (250-350 Å), and the tube can be viewed as a thin shell.
What I found is that the refinement didn’t converge in the first Helical refinement job with the correct symmetry (tiny search range for the rise and twist because it is calculated from layer lines at high resolution). However, if I copied this Helical refinement job, using exactly the same parameters and also using the output volume of the 1st job as input, the 2nd refinement will converge. Any thoughts? Currently, it didn’t create any problem for me, but one can imagine it may be an issue when one has 100 possible helical symmetries to test.
1st job (reported ~10Å)
2nd job (still going, ~3.3Å)