Adiabatic state preparation of correlated wave functions with nonlinear scheduling functions and broken-symmetry wave functions

Adiabatic state preparation (ASP) can generate correlated wave functions for quantum chemical calculations, but is inherently unsuitable for studying strongly correlated systems. Here, the authors perform numerical simulations of ASP for the ground state wave functions of molecules with strongly correlated electrons and propose practical conditions for preparation of close-to-exact correlated wave functions. Adiabatic state preparation (ASP) can generate the correlated wave function by simulating the time evolution of wave function under the time-dependent Hamiltonian that interpolates the Fock operator and the full electronic Hamiltonian. However, ASP is inherently unsuitable for studying strongly correlated systems, and furthermore practical computational conditions for ASP are unknown. In quest for the suitable computational conditions for practical applications of ASP, we performed numerical simulations of ASP in the potential energy curves of N-2, BeH2, and in the C-2v quasi-reaction pathway of the Be atom insertion to the H-2 molecule, examining the effect of nonlinear scheduling functions and the ASP with broken-symmetry wave functions with the S-2 operator as the penalty term, contributing to practical applications of quantum computing to quantum chemistry. Eventually, computational guidelines to generate the correlated wave functions having the square overlap with the complete-active space self-consistent field wave function close to unity are discussed.

Automated summary

In this study, numerical simulations of adiabatic state preparation (ASP) were performed to generate ground state wave functions for molecules with strongly correlated electrons. Practical conditions for close-to-exact correlated wave function preparation were proposed. The effect of nonlinear scheduling functions and ASP with broken-symmetry wave functions were examined, contributing to practical applications of quantum computing in quantum chemistry.