Scaled opposite-spin CC2 for ground and excited states with fourth order scaling computational costs.
Scaled opposite-spin CC2 for ground and excited states with fourth order scaling computational costs.
复制标题
具有四阶缩放计算成本的基态和激发态的缩放相反自旋 CC2。
DOI：
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发表时间：
2011
影响因子：
4.4
通讯作者：
C. Hättig
中科院分区：
文献类型：
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作者：
Nina O. C. Winter;C. Hättig
提出了一种对基态和激发态能量进行缩放的对自旋CC2 （SOS-CC2）的实现方法，其计算成本仅为四阶。SOS-CC2方法的结果精度与未标度方法相当。此外，该算法中决定时间的五阶缩放步骤可以使用电子排斥积分的“恒等分辨率”近似和轨道能量分母的拉普拉斯变换，仅用四阶缩放计算成本代替。这大大降低了计算成本，特别是对于大型系统。给出了基态和激发态计算的时序，并研究了拉普拉斯变换的误差。对含有134个原子的叶绿素分子的应用结果是5倍的加速，并演示了新的实现如何扩展了该方法的适用性。通过对SOS- cc2模型的简化，提出了利用二阶ADC(2)构造代数图的SOS变体。SOS-ADC(2)模型是一种经济有效的替代方案，特别是在未来扩展光谱强度和激发态结构优化方面。
An implementation of scaled opposite-spin CC2 (SOS-CC2) for ground and excited state energies is presented that requires only fourth order scaling computational costs. The SOS-CC2 method yields results with an accuracy comparable to the unscaled method. Furthermore the time-determining fifth order scaling steps in the algorithm can be replaced by only fourth order scaling computational costs using a "resolution of the identity" approximation for the electron repulsion integrals and a Laplace transformation of the orbital energy denominators. This leads to a significant reduction of computational costs especially for large systems. Timings for ground and excited state calculations are shown and the error of the Laplace transformation is investigated. An application to a chlorophyll molecule with 134 atoms results in a speed-up by a factor of five and demonstrates how the new implementation extends the applicability of the method. A SOS variant of the algebraic diagrammatic construction through second order ADC(2), which arises from a simplification of the SOS-CC2 model, is also presented. The SOS-ADC(2) model is a cost-efficient alternative in particular for future extensions to spectral intensities and excited state structure optimizations.