A simple script to compute Mollet-Plosset perturbation to any order in the FCI representation
Expected output:
converged SCF energy = -4.01106573767114
FCI energy -4.201971691548844
Number of determinants 4900
MP 1 total energy -4.0110657376711325
MP 2 total energy -4.121555265919251
MP 3 total energy -4.165124795837856
MP 4 total energy -4.185600817955428
MP 5 total energy -4.195199565071872
MP 6 total energy -4.199718767012338
MP 7 total energy -4.201608051169152
MP 8 total energy -4.202237097043432
MP 9 total energy -4.2023077188253835
MP 10 total energy -4.202200311475749
MP 11 total energy -4.202074287346094
MP 12 total energy -4.201988909294932
MP 13 total energy -4.201946735346703
MP 14 total energy -4.2019360129291305
MP 15 total energy -4.2019410762957685
MP 16 total energy -4.201951612945865
MP 17 total energy -4.201961356734178
MP 18 total energy -4.201968237591372
MP 19 total energy -4.201971995275865
MP 20 total energy -4.201973500176233