Only do pairwise energy conservation if there are two or more particles#6818
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JustinRayAngus merged 2 commits intoBLAST-WarpX:developmentfrom Apr 28, 2026
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LGTM.
Thanks, Dave.
JustinRayAngus
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With unequally weight particles in binary collisions, the particle momenta are adjusted to exactly conserve energy and momentum. The adjustment for energy conservation is done pairwise (within each species). This PR adds a check that there are at least two particles in the cell before calling the routine that does the energy correction. Without this check, an infinite loop can arise since due to round off, the relative energy can be negative.
Also, a check is added for the unlikely case where the relative energy is negative for all pairs of particles.