Quantum HF/DFT-embedding algorithms for electronic structure calculations: Scaling up to complex molecular systems.

Area of Science:

• Quantum chemistry
• Computational materials science
• Drug discovery

Background:

• Quantum computer-assisted simulations promise to revolutionize material and drug design.
• Current quantum computers are limited to simulating very simple molecules.
• Scaling quantum simulations to larger, more complex systems is a significant challenge.

Purpose of the Study:

• To develop and validate embedding schemes for quantum electronic structure calculations.
• To enable accurate simulations of larger molecular systems beyond the capabilities of current quantum hardware.
• To improve the efficiency and applicability of quantum computing in chemistry.

Main Methods:

• Embedding quantum electronic structure calculations within classical Hartree-Fock (HF) or Density Functional Theory (DFT) environments.
• Constructing an effective Hamiltonian with a mean-field potential for inactive electrons acting on an Active Space (AS).
• Utilizing the variational quantum eigensolver algorithm to determine the ground state of the AS Hamiltonian.

Main Results:

• Demonstrated significant energy corrections to reference HF and DFT calculations using the proposed embedding schemes.
• Successfully applied the methods to simple molecules in their strongly correlated (dissociation) limit.
• Validated the approach for systems of the size of the oxirane molecule.

Conclusions:

• The proposed HF and DFT embedding schemes effectively enhance quantum simulations for complex molecular systems.
• This approach overcomes the limitations of current quantum computer resources, enabling the study of larger molecules.
• The methods show promise for advancing material and drug design through more powerful quantum simulations.