Densest versus jammed packings of two-dimensional bent-core trimers

Abstract

We identify the maximally dense lattice packings of tangent-disk trimers with fixed bond angles ($\ensuremath{\theta}={\ensuremath{\theta}}_{0}$) 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 ${\ensuremath{\theta}}_{0}=0,\phantom{\rule{4pt}{0ex}}{60}^{\ensuremath{\circ}},\phantom{\rule{4pt}{0ex}}\mathrm{and}\phantom{\rule{4pt}{0ex}}{120}^{\ensuremath{\circ}}$ trimers can form the triangular lattice, maximally-dense maximally-symmetric packings for all ${\ensuremath{\theta}}_{0}$ fall into just two categories distinguished by their bond topologies: half-elongated-triangular for $0l{\ensuremath{\theta}}_{0}l{60}^{\ensuremath{\circ}}$ and elongated-snub-square for ${60}^{\ensuremath{\circ}}l{\ensuremath{\theta}}_{0}l{120}^{\ensuremath{\circ}}$. 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.