-1.6775             -2.0981             -2.5533             -2.9286             -3.3131
    2    -1.1310        -1.1543        -1.2396        -1.2646        -1.5036        -1.5194             -1.9720             -2.4606             -2.8716             -3.2976
    3    -0.9708        -0.9985        -1.0835        -1.1212        -1.3629        -1.3910             -1.8694             -2.3851             -2.8299             -3.2851
    4    -0.8409        -0.8702        -0.9577        -1.0066        -1.2473        -1.2892             -1.7870             -2.3237             -2.7945             -3.2751
    5    -0.7356        -0.7654        -0.8555        -0.9145        -1.1540        -1.2094             -1.7212             -2.2738             -2.7602             -3.2664
    6    -0.6501        -0.6798        -0.7746        -0.8395        -1.0790        -1.1463             -1.6688             -2.2329             -2.7369             -3.2594
    7    -0.5803        -0.6092        -0.7080        -0.7776        -1.0186        -1.0957             -1.6268             -2.1992             -2.7167             -3.2539
    8    -0.5226        -0.5504        -0.6538        -0.7261        -0.9697        -1.0546             -1.5926             -2.1711             -2.7000             -3.2498
    9    -0.4744        -0.5009        -0.6083        -0.6828        -0.9296        -1.0207             -1.5646             -2.1475             -2.6858             -3.2451
   10    -0.4339        -0.4588        -0.5707        -0.6459        -0.8953        -0.9924             -1.5414             -2.1275             -2.6737             -3.2421
   11    -0.3994        -0.4228        -0.5388        -0.6144        -0.8671        -0.9686             -1.5217             -2.1104             -2.6632             -3.2382
   12    -0.3696        -0.3916        -0.5114        -0.5871        -0.8410        -0.9483             -1.5050             -2.0956             -2.6541             -3.2354
   13    -0.3439        -0.3643        -0.4872        -0.5633        -0.8210        -0.9308             -1.4906             -2.0827             -2.6461             -3.2325
   14    -0.3214        -0.3405        -0.4671        -0.5424        -0.8036        -0.9157             -1.4780             -2.0715             -2.6390             -3.2305
   15    -0.3016        -0.3194        -0.4489        -0.5239        -0.7881        -0.9025             -1.4669             -2.0615             -2.6328             -3.2282

  : \[6x6\]Ground-state energy per particle for $6\times6$ lattice with different fillings and on-site repulsion, obtained with $\mathcal{PQGT}'$ conditions, compared with DMRG results for $N=36$, 34 and 30.

The 2D Hubbard model on a square lattice with periodic boundary conditions (PBC), [*i.e.*]{} 