Viral Capsid Self-Assembly

Icosahedral virus capsids assemble from dozens to hundreds of identical protein subunits without any central template, guided purely by geometry and weak, reversible protein-protein bonds. This simulator constructs the real Caspar-Klug geodesic lattice for a chosen T-number — 12 pentamers at the fixed 5-fold vertices plus 10(T−1) hexamers filling the 6-fold positions — and grows it with a nucleation-and-growth kinetic model: a free-floating pool of capsid protein subunits attaches preferentially next to already-formed neighbours, so assembly accelerates once a nucleus forms, while raising thermal agitation lets weakly-bonded subunits fall back off. Live readouts track how many capsomers have assembled, how many capsomer-capsomer bonds have formed, and the cumulative binding energy released as the shell closes.