  We use computational modeling to investigate the assembly thermodynamics of a
particle-based model for geometrically frustrated assembly, in which the local
packing geometry of subunits is incompatible with uniform, strain-free
large-scale assembly. The model considers discrete triangular subunits that
drive assembly towards a closed, hexagonal-ordered tubule, but have geometries
that locally favor negative Gaussian curvature. We use dynamical Monte Carlo
simulations and enhanced sampling methods to compute the free energy landscape
and corresponding self-assembly behavior as a function of experimentally
accessible parameters that control assembly driving forces and the magnitude of
frustration. The results determine the parameter range where finite-temperature
self-limiting assembly occurs, in which the equilibrium assembly size
distribution is sharply peaked around a well-defined finite size. The
simulations also identify two mechanisms by which the system can escape
frustration and assemble to unlimited size, and determine the particle-scale
properties of subunits that suppress unbounded growth.
