# Initial structure of four separated chains in a small space.

The initial structure consists of four separate chains confined in a small space. By using moltemplate [85], one chain was generated, and then, by using packmol [103], four copies of chains were placed in a cubic box with a size of *L* = 100*σ*. The polymer system was then compressed to a small spherical confinement radius of *R*_{c} = 20*σ* (or *ϕ* = 0.6) using indented walls and Lennard-Jones (LJ) interactions. The force exerted by a spherical indenter on each bead is represented by the equation *F*(*r*) = −*K*_{indent}(*r* − *R*_{indent})^{2}, where *K*_{indent} is the specified force constant, *r* is the distance from the bead to the center of the indenter, and *R*_{indent} is the radius of the indenter [83]. The intra-chain interactions were attractive, with a strength of *ϵ*_{intra} = 1*k*_{B}*T* and a cutoff distance of *r*_{c} = 2.5*σ*, while the inter-chain interactions were repulsive, with a strength of *ϵ*_{inter} = 1*k*_{B}*T* and a cutoff distance of *r*_{c} = 2^{1/6}*σ*. A snapshot of the initial structure is shown in a confinement with a volume fraction of *ϕ* = 0.1, which illustrates that the chains were initially separated and condensed.

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