Dr. James (Jim) Francis Belak

Dr. James (Jim) Francis Belak died on Jan. 22, 2026. He was 68.

He was born on Nov. 27, 1957, in Philadelphia, to Charles and Ann Belak. After graduating from Rutgers University with a double major in mathematics and physics, he moved to Fort Collins, Colorado, to pursue his doctor of philosophy in physics at Colorado State University (CSU). After a post-doctoral appointment at Johns Hopkins University, he joined Lawrence Livermore National Laboratory (LLNL) in 1989, where he worked for the following 35 years. At the time of his retirement in 2024, he was a senior scientist in the Materials Science Division at LLNL. He worked to apply materials simulation (molecular dynamics, Monte Carlo, phase-field, microstructure evolution, and continuum mechanics) and synchrotron x-ray techniques (3D tomography, small-angle scattering and in situ diffraction) to quantify dynamic material behavior in extreme conditions. He was co-PI on the original LAMMPs CRADA, and most recently, he co-led (along with Tim German from Los Alamos National Laboratory) the DOE/ASCR Exascale Co-design Center for Materials in Extreme Environments (ExMatEx).

He is survived by his wife Diane, his children Carolyn Belak and Brian Belak (spouse Rachel Whaley), and his siblings Chuck and Joanne. Upon his request, no formal service will be held. In lieu of flowers, the Belak family requests that those wishing to honor his memory support their local environmental advocacy organizations.