Molecular admission and packing govern transport in subnanometre graphene slits

The nominal slit width is not equivalent to molecular accessibility. The reservoir-fed molecular dynamics of Lennard-Jones argon at 100 K in rigid five-layer graphene slits (w = 0.396-3.40 nm) separate three quantities that confined-fluid descriptions routinely merge: energetic accessibility of the slit interior, observed molecular admission, and stationary post-admission capacity. Cutoff-consistent lattice summation over the production carbon coordinates places the laterally averaged one-body zero crossing at , registry extrema 0.5700 and 0.5859 nm. No entry occurs at w = 0.575 nm over 35.38 ns or at 0.580 nm over 406.98 ns, whereas 0.590 nm admits argon after 7.595 ns and remains occupied for 99.92% of its post-entry record, giving an observation-dependent sustained-admission bracket 0.580 < wobsadm ≤ 0.590 nm. Near this admission boundary, loading remains nonstationary after approximately 1 µs, and the terminal-window attained accessibilities of K_term50 = 0.0475, 0.2007, and 0.5282 at w = 0.590, 0.592, and 0.594 nm, respectively. Where loading is stationary, packing governs capacity: layer splitting near w_flip = 0.773 nm produces a statistically resolved accessibility minimum (pooled K = 0.540 over w = 0.745-0.808 nm), and wide slits follow a capacity envelope Γ = a(w - δ_dead), a = 20.85 ± 0.48 atoms nm^-3, and δ_dead = 0.328 ± 0.029 nm. Under a fixed-displacement-rate drive, the apparent conductance decreased 23.7-fold toward admission. Therefore, accessibility, admission, stationary loading, and capacity are distinct conditions, not one geometric threshold.