BQ-Chem: A Quantum Software Program for Chemistry Simulation Based on the Full Quantum Eigensolver Algorithm

Figure 3

The resulting energy spectrum of the ground state (blue dotted line) and up to the 3rd excitation state (green, yellow, and red dotted line) of in BQ-Chem. Each dotted line converges monotonically to the theoretical value of the exact Hamiltonian diagonalization energy (red-solid line), respectively. To be noted, the 1st excitation energy curve (green) is covered by the 2nd excitation energy curve (yellow) of molecule due to their degeneracy; thus, the green line cannot be seen directly.