Vibrational spectra and wavefunctions of polyatomic molecules can be calculated at low memory cost using low-rank sum-of-product (SOP) decompositions to represent basis functions generated using an iterative eigensolver. Using a SOP tensor format does not determine the iterative eigensolver. The choice of the interative eigensolver is limited by the need to restrict the rank of the SOP basis functions at every stage of the calculation. We have adapted, implemented and compared different reduced-rank algorithms based on standard iterative methods (block-Davidson algorithm, Chebyshev iteration) to calculate vibrational energy levels and wavefunctions of the 12-dimensional acetonitrile molecule. The effect of using low-rank SOP basis functions on the different methods is analyzed and the numerical results are compared with those obtained with the reduced rank block power method introduced in J. Chem. Phys. 140, 174111 (2014). Relative merits of the different algorithms are presented, showing that the advantage of using a more sophisticated method, although mitigated by the use of reduced-rank sum-of-product functions, is noticeable in terms of CPU time.
Using quadrature and an iterative eigensolver to compute fine-structure ro-vibrational levels of Van der Waals complexes: NH($^3Σ^-$)-He, O$_2$($^3Σ^-_g$)-Ar and O$_2$($^3Σ^-_g$)-He
Machine Learning for Vibrational Spectroscopy via Divide-and-Conquer Semiclassical Initial Value Representation Molecular Dynamics with Application to N-Methylacetamide
Influences of quantum mechanically mixed electronic and vibrational pigment states in 2D electronic spectra of photosynthetic systems: Strong electronic coupling cases
Impact of environmentally induced fluctuations on quantum mechanically mixed electronic and vibrational pigment states in photosynthetic energy transfer and 2D electronic spectra
最近，在2D电子光谱中的核振动贡献签名已经引起了相当大的兴趣，特别是在光捕获复合物中观察到的振荡瞬态的解释方面。这些瞬变具有持续比理论上预测的电子相干寿命长得多的退相时间。作为对2D电子光谱中的这种长寿命光谱跳动的合理解释，Christensson等人[J. Phys. Chem. B 116，7449（2012）]提出了量子力学混合的电子和振动态（振动激子），并且此后进行了探索。在这项工作中，我们解决了一个二聚体，产生小跳动的电子起源的情况下，振动的贡献，并检查蛋白质诱导的波动后，电子振动量子混合物的影响，通过计算电子能量转移动力学和二维电子光谱在数值上准确的方式。研究发现，在低温下，电子-振动量子混合物是相当稳健的，即使在涨落的影响下，尽管Franck-Condon活动振动模式的Huang-Rhys因子很小.这导致在2D电子光谱中振动源的持久的拍频行为。然而，在生理温度下，波动消除了混合，因此，2D光谱中的跳动消失了。此外，它表明，这样的电子振动量子混合物不一定在电子能量转移动力学中发挥重要作用，尽管有助于增强长寿命的量子拍在二维电子光谱，在最近的出版物中的猜测相反。
