Center for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
J Chem Phys. 2010 Jun 14;132(22):224503. doi: 10.1063/1.3454733.
We introduce a sparse-matrix algorithm that allows for the simulation of two-dimensional infrared (2DIR) spectra in systems with many coupled chromophores. We apply the method to bulk water, and our results are based on the recently developed ab initio maps for the vibrational Hamiltonian. Qualitative agreement between theory and experiment is found for the 2DIR spectra without the use of any fitting or scaling parameters in the Hamiltonian. The calculated spectra for bulk water are not so different from those for HOD in D(2)O, which we can understand by considering the spectral diffusion time-correlation functions in both cases. We also calculate the ultrafast anisotropy decay, which is dominated by population transfer, finding very good agreement with experiment. Finally, we determine the vibrational excitation diffusion rate, which is more than two orders of magnitude faster than the diffusion of the water molecules themselves.
我们介绍了一种稀疏矩阵算法，该算法可用于模拟具有多个耦合发色团的二维红外（2DIR）光谱。我们将该方法应用于体相水，并且我们的结果基于最近为振动哈密顿量开发的从头算图谱。在不使用哈密顿量中的任何拟合或缩放参数的情况下，理论与实验之间的 2DIR 光谱具有定性的一致性。对于体相水，计算得到的光谱与 D（2）O 中的 HOD 的光谱没有太大区别，我们可以通过考虑两种情况下的光谱扩散时间相关函数来理解这一点。我们还计算了超快各向异性衰减，其主要由种群转移决定，发现与实验非常吻合。最后，我们确定了振动激发扩散率，它比水分子本身的扩散速度快两个数量级以上。
