Enhancing Accuracy of Quantum-Selected Configuration Interaction Calculations Using Multireference Perturbation...

Area of Science:

• Quantum computing
• Computational chemistry
• Theoretical chemistry

Background:

• Quantum-selected configuration interaction (QSCI) is a hybrid quantum-classical algorithm for quantum chemistry.
• QSCI identifies key electron configurations using quantum devices for classical computation, aiming to manage large configuration spaces and mitigate noise.
• Current QSCI limitations include qubit noise affecting accuracy in small active spaces.

Purpose of the Study:

• To demonstrate a computational scheme to improve the accuracy of QSCI calculations.
• To apply this scheme to ground and excited state calculations of aromatic molecules.
• To investigate methods for further accuracy enhancement.

Main Methods:

• Developed a computational scheme using multireference perturbation theory on classical computers.
• Utilized the QSCI wave function as a reference for perturbation calculations.
• Applied the method to naphthalene and tetracene for ground and excited state analysis.

Main Results:

• The incorporation of perturbation theory significantly improved the accuracy of QSCI calculations.
• The method was successfully applied to calculate ground and excited states of naphthalene and tetracene.
• Investigated extending the reference space using QSCI-selected configurations for further accuracy gains.

Conclusions:

• The developed computational scheme enhances the accuracy of QSCI for quantum chemistry.
• This hybrid approach shows promise for more accurate calculations of molecular electronic structures.
• Further research can explore reference space extension for even greater precision.