  Computer modeling is essential to research on Advanced Accelerator Concepts
(AAC), as well as to their design and operation. This paper summarizes the
current status and future needs of AAC systems and reports on several key
aspects of (i) high-performance computing (including performance, portability,
scalability, advanced algorithms, scalable I/Os and In-Situ analysis), (ii) the
benefits of ecosystems with integrated workflows based on standardized input
and output and with integrated frameworks developed as a community, and (iii)
sustainability and reliability (including code robustness and usability).
