We identify the maximally dense lattice packings of tangent-disk trimers with fixed bond angles (θ = θ0) and contrast them to both their nonmaximally-dense-but-strictly-jammed lattice packings as well as the disordered jammed states they form for a range of compression protocols. While only θ0 = 0, 60 • , and 120 • trimers can form the triangular lattice, maximally-dense maximallysymmetric packings for all θ0 fall into just two categories distinguished by their bond topologies: half-elongated-triangular for 0 < θ0 < 60 • and elongated-snub-square for 60 • < θ0 < 120 •. The presence of degenerate, lower-symmetry versions of these densest packings combined with several families of less-dense-but-strictly-jammed lattice packings act in concert to promote jamming.

We identify putatively maximally dense packings of tangent-sphere trimers with fixed bond angles (θ = θ0) using a novel method, and contrast them to the disordered jammed states they form under quasistatic and dynamic athermal compression. Incommensurability of θ0 with 3D closepacking does not by itself inhibit formation of dense 3D crystals; all θ0 allow formation of crystals with φmax(θ0) > 0.97φcp. Trimers are always able to arrange into periodic structures composed of close-packed bilayers or trilayers of triangular-lattice planes, separated by "gap layers" that accomodate the incommensurability. All systems have φJ significantly below the monomeric value, indicating that trimers' quenched bond-length and bond-angle constraints always act to promote jamming. φJ varies strongly with θ0; straight (θ0 = 0) trimers minimize φJ while closed (θ0 = 120 • ) trimers maximize it. Marginally jammed states of trimers with lower φJ (θ0) exhibit quantifiably greater disorder, and the lower φJ for small θ0 is apparently caused by trimers' decreasing effective configurational freedom as they approach linearity. arXiv:1907.00035v1 [cond-mat.soft]