Model specification: Frozen P8

Set $n=8$, $g=1$. Enumerate the $1820$ increasing quartets of $\{1,\dots ,16\}$ lexicographically and define

Order exact even-sector eigenspaces by energy. Within each exact degenerate eigenspace, project lexicographic occupation words and apply Gram–Schmidt, discarding zero projections. Give each vector a first nonzero occupation coefficient that is positive real. Select the first two vectors.

Retain the global energy shift over both parities, spectral window $[0,2h_4]$, $t_0=\Omega =T=1$, bath vacuum, and signed whole-bath access.