The National Center for Multiscale Modeling of Biological Systems (MMBioS), and the National Resource for Biomedical Supercomputing (NRBSC) at the Pittsburgh Supercomputing Center (PSC) are soliciting proposals for computer time on Anton, a special-purpose supercomputer for molecular dynamics (MD) simulation designed by D. E. Shaw Research (DESRES). A 512-node Anton machine is currently available and in production use at the PSC. The machine has been made available without cost by DESRES for non-commercial research use by universities and other not-for-profit institutions, and is hosted by NRBSC. Operational funding is provided by NIGMS through MMBioS, a joint effort between the University of Pittsburgh, PSC, Carnegie Mellon University, and the Salk Institute. To qualify for an allocation on Anton, the principal investigator (PI) must be a faculty or staff member at a U.S. academic or non-profit research institution and must have the appropriate level of authority and responsibility to direct the project supported by the allocation. A graduate student or postdoctoral researcher may not be a PI, but a qualified advisor may apply for an allocation on her or his behalf. Furthermore, each investigator can serve as a PI for only a single application for computer time on Anton. PIs who previously had an allocation on Anton at NRBSC are strongly encouraged to apply but are required to provide a detailed (2-3 page) progress report of their past work on the Anton machine at NRBSC. Repeat applications unaccompanied by a progress report will not be considered. The deadline for applications is 11:59 p.m., EDT, Tuesday, May 28, 2013. For complete details, including proposal requirements and submission instructions, see the NRBSC web site at http://www.nrbsc.org/anton_rfp/.