ChimeraX and Chimera are different programs, with different interfaces and capabilities that overlap significantly, but not completely. ChimeraX has capabilities that go far beyond those in Chimera, including completely new tools and other major advantages such as better performance on large data. ChimeraX is under active development and is based on modern software frameworks that extend its life far into the future. By contrast, Chimera has reached end-of-life and is no longer being developed or supported. Further, some Chimera tools that rely on web services may stop working entirely because the infrastructure they depend on is obsolete (details...).
While ChimeraX has new areas of application and far greater capabilities than Chimera, it is also intended to serve as a replacement for Chimera for most users. ChimeraX includes most of the highly used Chimera features (with more to come, see below), often with significant enhancements in their function and/or usability. Not all Chimera features will be implemented, however, only those which are highly used and relevant to modern use.
We encourage Chimera users to try ChimeraX.
Salient missing features relative to Chimera currently include:
ChimeraX will contain more of these important features as development proceeds. As alluded to above, some features are currently implemented in ChimeraX as commands only, not yet as graphical interfaces. For lists of the current tools and commands in each program, see the respective User Guides: [ChimeraX] [Chimera] See also the ChimeraX change log
Although similar in many aspects, ChimeraX is not backward compatible with Chimera and does not read Chimera session files. However, Chimera includes an export to ChimeraX feature that covers some but not all types of data.