Workflow for practical quantum chemical calculations with quantum phase estimation algorithm: electronic ground and {\pi}-{\pi}* excited states of benzene and its derivatives{\dag}

TL;DR

This paper develops a practical workflow for quantum phase estimation-based quantum chemical calculations, demonstrating simulations of benzene derivatives' electronic states with GPGPU acceleration, and establishing a standard approach for practical molecules.

Contribution

The paper introduces a comprehensive, adaptable workflow for QPE quantum chemical calculations, including basis selection, active space configuration, and error reduction techniques, applicable to practical molecules.

Findings

Successfully simulated ground and excited states of benzene derivatives using QPE

Implemented GPGPU acceleration to enhance simulation efficiency

Proposed a standard, adaptable workflow for practical quantum chemical calculations

Abstract

Quantum computers are expected to perform the full-configuration interaction calculations with less computational resources compared to classical ones, thanks to the use of the quantum phase estimation (QPE) algorithms. However, only a limited number of the QPE-based quantum chemical calculations have been reported even for numerical simulations on a classical computer, and the practical workflow for the QPE computation has not yet been established. In this paper, we report the QPE simulations of the electronic ground and the {\pi}-{\pi}* excited singlet state of benzene and its chloro- and nitroderivatives as the representative industrially important systems, with the aid of GPGPU acceleration of quantum circuit simulations. We adopted the pseudo-natural orbitals obtained from the MP2 calculation as the basis for the wave function expansion, the CISD calculation within the active space to find the main electronic configurations to be included in the input wave function of the excited state, and the technique to reduce the truncation error the calculated total energies. The proposed computational workflow is easily applicable to other molecules and can be a standard approach for performing the QPE-based quantum chemical calculations of practical molecules.