Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected Time-Dependent Density Functional Tight Binding
Efficient Calculation of Electronic Absorption Spectra by Means of Intensity-Selected Time-Dependent Density Functional Tight Binding
复制标题
DOI：
10.1021/ct500838h
复制
发表时间：
2015-01-01
影响因子：
5.5
通讯作者：
Visscher, Lucas
中科院分区：
文献类型：
--
作者：
Ruger, Robert;van Lenthe, Erik;Visscher, Lucas
在过去的二十年中，基于密度泛函的线性响应方法已经成为计算中小分子光学性质的事实上的标准。这些方法的核心是在单轨道跃迁空间中求解本征值方程，单轨道跃迁的数量迅速增加，使得这种计算成本高昂，如果不是对较大分子不可行的话。这对于依赖时间的密度泛函紧束缚（TD-DFTB）尤其如此，其中矩阵元素的评估是廉价的。因此，对于可以研究的相对较大的系统，本征值方程的解决定了计算的成本。我们建议做一个基于振子强度截断的单轨道过渡空间，以减少计算工作的TD-DFTB为基础的吸收光谱计算。我们表明，即使是一个相当大的截断不破坏的吸收光谱的主要特征，同时自然地避免了不必要的计算小振子强度的激发。我们认为，强度选择TD-DFTB的计算成本降低，加上其易用性相比，其他方法降低了执行大分子的光学性质计算的障碍，并可以用于使这种计算可能在更广泛的应用。
During the last two decades density functional based linear response approaches have become the de facto standard for the calculation of optical properties of small and medium-sized molecules. At the heart of these methods is the solution of an eigenvalue equation in the space of single-orbital transitions, whose quickly increasing number makes such calculations costly if not infeasible for larger molecules. This is especially true for time-dependent density functional tight binding (TD-DFTB), where the evaluation of the matrix elements is inexpensive. For the relatively large systems that can be studied the solution of the eigenvalue equation therefore determines the cost of the calculation. We propose to do an oscillator strength based truncation of the single-orbital transition space to reduce the computational effort of TD-DFTB based absorption spectra calculations. We show that even a sizeable truncation does not destroy the principal features of the absorption spectrum, while naturally avoiding the unnecessary calculation of excitations with small oscillator strengths. We argue that the reduced computational cost of intensity-selected TD-DFTB together with its ease of use compared to other methods lowers the barrier of performing optical properties calculations of large molecules, and can serve to make such calculations possible in a wider array of applications.