I applied online through the Department of Energy website, and selected LBNL as my first choice. The application requires letters of recommendations, transcripts, and essays. This was a pretty standard application for research internships. A few weeks after I applied, I was contacted by a research scientist. They said that they were considering my application, but they wanted to have a phone interview before offering me a position. I did a phone interview with that scientist, and they asked me questions about my personality and work style, and questions about my experience (which really was just the classes I had taken up to that point). After that, I received a formal offer via email, which I accepted.