$T$ -矩阵近似下的静态和动态Bethe-Salpeter方程
Static and Dynamic Bethe-Salpeter Equations in the $T$-Matrix Approximation
摘要：
虽然建立良好的$GW$近似对应于直接环图的再确认，并且特别适合于弱相关系统，但$T$矩阵近似确实将梯形图求和到无穷大，并且在强相关存在的情况下更合适。在这里，我们推导并实现，第一次，静态和动态的Bethe-Salpeter方程时，一个考虑$T$矩阵准粒子能量以及一个$T$矩阵为基础的内核。通过计算分子系统的中性激发态，评价了静态格式的性能及其微扰动力学修正。与更传统的计划，以及其他波函数方法的比较也有报道。我们的研究结果表明，$T$矩阵为基础的形式主义表现最好的少电子系统中的电子密度仍然很低。
英文摘要：
While the well-established $GW$ approximation corresponds to a resummation of the direct ring diagrams and is particularly well suited for weakly-correlated systems, the $T$-matrix approximation does sum ladder diagrams up to infinity and is supposedly more appropriate in the presence of strong correlation. Here, we derive and implement, for the first time, the static and dynamic Bethe-Salpeter equations when one considers $T$-matrix quasiparticle energies as well as a $T$-matrix-based kernel. The performance of the static scheme and its perturbative dynamical correction are assessed by computing the neutral excited states of molecular systems. Comparison with more conventional schemes as well as other wave function methods are also reported. Our results suggest that the $T$-matrix-based formalism performs best in few-electron systems where the electron density remains low.
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