Determining the properties of molecules and materials is one of the premier applications of quantum computing. A major question in the field is how to use imperfect near-term quantum computers to solve problems of practical value. Inspired by the recently developed variants of the quantum counterpart of the equation-of-motion (qEOM) approach and the orbital-optimized variational quantum eigensolver (oo-VQE), we present a quantum algorithm (oo-VQE-qEOM) for the calculation of molecular properties by computing expectation values on a quantum computer. We perform noise-free quantum simulations of BeH₂ in the series of STO-3G/6-31G/6-31G* basis sets and of H₄ and H₂O in 6-31G using an active space of four electrons and four spatial orbitals (8 qubits) to evaluate excitation energies, electronic absorption, and, for twisted H₄, circular dichroism spectra. We demonstrate that the proposed algorithm can reproduce the results of conventional classical CASSCF calculations for these molecular systems.

中文翻译：

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近期量子计算中用于计算分子特性的轨道优化的量子运动方程

确定分子和材料的特性是量子计算的主要应用之一。该领域的一个主要问题是如何利用不完善的近期量子计算机来解决具有实用价值的问题。受最近开发的运动方程（qEOM）方法的量子对应变体和轨道优化变分量子本征解算器（oo-VQE）的启发，我们提出了一种用于计算的量子算法（oo-VQE-qEOM）通过在量子计算机上计算期望值来了解分子特性。我们使用四个电子和四个空间的活动空间对STO-3G/6-31G/6-31G* 基组系列中的BeH _{2以及 6-31G 中的 H 4}和 H ₂ O进行无噪声量子模拟。轨道（8 个量子位）来评估激发能、电子吸收，以及扭曲的 H ₄圆二色光谱。我们证明所提出的算法可以重现这些分子系统的传统经典 CASSCF 计算的结果。