Investigating potential energy surfaces of noncollinear molecule using variational quantum circuit

TL;DR

This paper demonstrates high-accuracy simulation of a noncollinear molecule's potential energy surface using variational quantum algorithms, achieving results comparable to exact methods and leveraging quantum runtime speedups.

Contribution

It introduces a method for simulating noncollinear molecules' PES with VQE, including optimization strategies for initial parameters to improve accuracy and efficiency.

Findings

Achieved chemical accuracy in PES simulation of H2O.

Successfully reported 2D and 3D PES maps.

Matched results with exact diagonalization.

Abstract

We demonstrate the simulation of a noncollinear molecule, e.g. H2O molecule using Variational Quantum Eigensolver (VQE) with high chemical accuracy. The 2D and 3D potential energy surface (PES) were reported. Taking advantage of the potential speedup in Qiskit runtime program, the optimal initial parameters for the variational quantum circuits were obtained after several consecutive iterations, thus resulting in accurate prediction of water's PES matching result obtained from exact diagonalization of the full Hamiltonian.