Optical Spectrum Analysis of Real-Time TDDFT Using the Maximum Entropy Method

25th IUPAP Conference on Computational Physics

物理学;计算机科学

Toogoshi, M.^1 ; Kato, M.^1 ; Kano, S.S.^1 ; Zempo, Y.^1

Computer and Information Sciences, Hosei University, 3-7-2 Kajino, Koganei 184-8584, Japan^1

关键词: Effectiveness and efficiencies;    High resolution;    Optical spectrum analysis;    Oscillator strengths;    Time dependent density functional theory;    Time evolutions;    Time-dependent equations;    Time-series data;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/510/1/012027/pdf
DOI  :  10.1088/1742-6596/510/1/012027

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

In the calculation of time-dependent density-functional theory in real time, we apply an external field to perturb the optimized electronic structure, and follow the time evolution of the dipole moment to calculate the oscillator strength distribution. We solve the time-dependent equation of motion, keeping track of the dipole moment as time-series data. We adopt Burg's maximum entropy method (MEM) to compute the spectrum of the oscillator strength, and apply this technique to several molecules. We find that MEM provides the oscillator strength distribution at high resolution even with a half of the evolution time of a simple FFT of the dynamic dipole moment. In this paper we show the effectiveness and efficiency of MEM in comparison with that of FFT. Not only the total number of time steps, but also the length of the autocorrelation, the lag, plays an important role in improving the resolution of the spectrum.