Subcritical Pitchfork Bifurcation Transition of a Single Nanoparticle in Strong Confinement

Confinement influences fluid properties. We show, employing molecular dynamics simulations with explicit solvents, that slit confinement drives a first-order transition for a small nanoparticle between staying at the slit center and binding to the slit surfaces. The transition follows a subcritical pitchfork bifurcation, accompanying a similar transition of the nanoparticle's lateral diffusion, depending on interparticle interactions and confinement interfaces. Our findings underscore the necessity for advancing molecular hydrodynamics under strong confinement.