Jeziorski-Monkhorst完全非收缩多参考微扰处理I：原理、二阶形式和基态potential energy曲线检验
A Jeziorski-Monkhorst fully uncontracted Multi-Reference perturbative treatment I: principles, second-order versions and tests on ground state potential energy curves
摘要：
本文介绍了一种新的多参考扰动方法，在二阶，基于Jeziorsky-Mokhorst扩展使用个人斯莱特行列式作为扰动。由于扰动器的这种选择，可以建立有效的哈密顿算子，允许在参考空间内修饰哈密顿矩阵，这里假设为CAS-CI。这样一个公式，然后帐户之间的耦合静态和动态的相关性的影响。根据我们对零阶能量的新定义，只要使用定域轨道，这两种方法都是严格的尺寸扩展方法，正如这里的数值说明和附录中的正式证明。此外，本形式主义允许因式分解的所有双激发算子，就像在内部收缩的方法，大大降低了计算成本，这两种方法相对于其他基于行列式的微扰理论。这些方法的准确性进行了研究，基态电位曲线上的一组六个分子，涉及单，双，三键断裂的完全解离极限。用本方法得到的光谱常数与全组态相互作用（FCI）的结果非常吻合。由于本方法不使用任何参数或数值不稳定操作，因此两种方法得到的曲线在整个解离路径上都是光滑的。
英文摘要：
The present paper introduces a new multi-reference perturbation approach developed at second order, based on a Jeziorsky-Mokhorst expansion using individual Slater determinants as perturbers. Thanks to this choice of perturbers, an effective Hamiltonian may be built, allowing for the dressing of the Hamiltonian matrix within the reference space, assumed here to be a CAS-CI. Such a formulation accounts then for the coupling between the static and dynamic correlation effects. With our new definition of zeroth-order energies, these two approaches are strictly size-extensive provided that local orbitals are used, as numerically illustrated here and formally demonstrated in the appendix. Also, the present formalism allows for the factorization of all double excitation operators, just as in internally contracted approaches, strongly reducing the computational cost of these two approaches with respect to other determinant-based perturbation theories. The accuracy of these methods has been investigated on ground-state potential curves up to full dissociation limits for a set of six molecules involving single, double and triple bond breaking. The spectroscopic constants obtained with the present methods are found to be in very good agreement with the full configuration interaction (FCI) results. As the present formalism does not use any parameter or numerically unstable operation, the curves obtained with the two methods are smooth all along the dissociation path.
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