We propose an orbital optimized method for unitary coupled cluster theory (OO-UCC) within the variational quantum eigensolver (VQE) framework for quantum computers. OO-UCC variationally determines the coupled cluster amplitudes and also molecular orbital coefficients. Owing to its fully variational nature, first-order properties are readily available. This feature allows the optimization of molecular structures in VQE without solving any additional equations. Furthermore, the method requires smaller active space and shallower quantum circuits than UCC to achieve the same accuracy. We present numerical examples of OO-UCC using quantum simulators, which include the geometry optimization of water and ammonia molecules using analytical first derivatives of the VQE.

中文翻译：

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量子计算机的轨道优化unit耦合簇理论

我们为量子计算机提出了一种变分量子本征求解器（VQE）框架中的coupled合簇理论（OO-UCC）的轨道优化方法。OO-UCC可变地确定耦合的簇振幅以及分子轨道系数。由于其完全可变的性质，一阶特性很容易获得。此功能允许优化VQE中的分子结构，而无需求解任何其他方程式。此外，该方法需要比UCC更小的有源空间和更浅的量子电路，以实现相同的精度。我们提供了使用量子模拟器的OO-UCC数值示例，其中包括使用VQE的解析一阶导数对水和氨分子进行几何优化。