According to modern models, what factor, besides initial mass, directly determines the 'explodability' of a massive star?

Answer

Its compactness

Modern models suggest that the explodability of a massive star is determined more directly by its compactness—how densely its material is packed in the center—and the structure of its final silicon-oxygen interface.

According to modern models, what factor, besides initial mass, directly determines the 'explodability' of a massive star?
astronomystarstellar evolutionsupernovamass