Quantum Solvers for Plane-Wave Hamiltonians: Abridging Virtual Spaces Through the Optimization of Pairwise...

Area of Science:

• Quantum Chemistry
• Computational Physics
• Materials Science

Background:

• Standard quantum chemistry methods like select configuration interaction (CI) and coupled cluster (CC) require robust virtual spaces to accurately model electron-electron correlation.
• Pseudopotential plane-wave Hartree-Fock calculations often yield virtual orbitals with weak interactions, limiting their ability to capture correlation energy.

Purpose of the Study:

• To develop novel algorithms for defining virtual spaces that can significantly improve the accuracy of quantum computing methods.
• To investigate the efficacy of these new virtual spaces, termed correlation optimized virtual orbitals (COVOs), for achieving full CI (FCI) quality results.

Main Methods:

• Developed new algorithms to define virtual spaces by optimizing orbitals from small pairwise CI Hamiltonians, creating correlation optimized virtual orbitals (COVOs).
• Applied COVOs to target FCI quality results for H2 using both FCI and quantum simulations on near-term quantum computers.

Main Results:

• Derived virtual spaces with only a few COVOs that capture a significant amount of electron correlation.
• Achieved good agreement with FCI/cc-pVTZ results for H2 using just 4 virtual orbitals, demonstrating the potential of the COVO approach.

Conclusions:

• Correlation optimized virtual orbitals (COVOs) offer a promising strategy for enhancing the accuracy of quantum computing methods in electronic structure calculations.
• The COVO approach may be applicable to other many-body methods and pseudopotential plane-wave basis set calculations, broadening their utility.