Coupled-cluster as well as equation-of-motion coupled-cluster methods play an important role whenever high accuracy is warranted. Concerning excitation energies, consideration of triple excitations is typically required to reach an accuracy better than 0.1–0.3 eV. In the context of strong magnetic fields such accuracy is needed for the prediction of spectra of strongly magnetized White Dwarfs. In addition it turns out that in order to correctly model the behavior of energies with respect to the magnetic field strength, triple excitations are required. Due to avoided crossings which are extremely often encountered in the context of strong magnetic fields, double-excitation character can be transferred between electronic states of the same symmetry. We report an implementation of the full finite-field coupled-cluster with single, double, and triple substitutions (CCSDT) and the equation-of-motion-CCSDT models and apply them to the prediction of field-dependent transition wavelengths for sodium as well as to the four lowest singlet states of the CH⁺ molecule in a strong magnetic field.

中文翻译：

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强磁场中原子和分子的耦合簇和运动方程耦合簇方法的全三元贡献

只要需要高精度，耦合群集以及运动方程耦合群集方法都将发挥重要作用。关于激发能量，通常需要考虑三次激发才能达到优于0.1–0.3 eV的精度。在强磁场的情况下，需要这种精度来预测强磁化白矮星的光谱。此外，事实证明，为了正确地模拟相对于磁场强度的能量行为，需要三次激发。由于避免了在强磁场中经常遇到的交叉现象，因此可以在相同对称性的电子状态之间传递双激励特性。我们报告了单，双，⁺分子在强磁场中。