I believe ClearCase/ClearQuest are no longer supported by IBM.
My company migrated to IBM's Jazz platform back in 2013. From my understanding Jazz platform is the underlying technology that allows application modules (RTC, DNG, RQM) to integrate; see https://jazz.net/story/about/about-jazz-platform.jsp
Rational Team Concert (RTC) is composed of: SCM, planning, work-item management, build management
Doors Next Generation (DNG) replaces Rational DOORS for requirements management.
Rational Quality Manager (RQM) is their test management solution to compete to with HP’s ALM.
Additionally, RTC and DNG also include “Review” functionality.
What’s interesting about jazz platform is that applications can link (“Collaborate”) to artifacts in the other applications via the jazz platform using REST API. So, Stories in RTC can link to Requirements in DNG and Test Cases in RQM – providing end-to-end traceability. They have now added “Global Configuration” concept which allows artifacts across these applications to be configured in the same way as source-code (steams, baselines).
The jazz platform with (RTC, DNG, RQM) is a “swiss-army knife” aimed at product development and can be daunting for someone that just wants use it for SCM.
I found 'Developer’s Guide to Rational Team Concert & Jazz Source Control' quite useful.
You can setup an account on jazz.net and “Try” these applications on their cloud on jazz.net.