Are you referring to a NEW composition by Libermann, or the Rachmaninoff Rhapsody on a Theme by Paganini? I assume you are referring to the former, and therefore Richter, Rubinstein, Pletnev, or Ashkenazy wouldn't have recorded this peice. However, that being the case, I have never heard of this new composition. It seems a bit redundant to compose yet ANOTHER major peice an a theme by Paganini, as that has been done quite frequently in the past.
Is Libermann a well-known composer? I haven't heard of him or his works. Am I missing anything important?