Hauge Eirill, Kristiansen Håkon Emil, Konecny Lukas, Kadek Marius, Repisky Michal, Pedersen Thomas Bondo
Hylleraas Centre for Quantum Molecular Sciences, Department of Chemistry, University of Oslo, P.O. Box 1033, Blindern, 0315 Oslo, Norway.
Department of Numerical Analysis and Scientific Computing, Simula Research Laboratory, Kristian Augusts Gate 23, 0164 Oslo, Norway.
J Chem Theory Comput. 2023 Nov 14;19(21):7764-7775. doi: 10.1021/acs.jctc.3c00727. Epub 2023 Oct 24.
We present a novel function fitting method for approximating the propagation of the time-dependent electric dipole moment from real-time electronic structure calculations. Real-time calculations of the electronic absorption spectrum require discrete Fourier transforms of the electric dipole moment. The spectral resolution is determined by the total propagation time, i.e., the trajectory length of the dipole moment, causing a high computational cost. Our developed method uses function fitting on shorter trajectories of the dipole moment, achieving arbitrary spectral resolution through extrapolation. Numerical testing shows that the fitting method can reproduce high-resolution spectra by using short dipole trajectories. The method converges with as little as 100 a.u. dipole trajectories for some systems, though the difficulty converging increases with the spectral density. We also introduce an error estimate of the fit, reliably assessing its convergence and hence the quality of the approximated spectrum.
我们提出了一种新颖的函数拟合方法，用于近似实时电子结构计算中随时间变化的电偶极矩的传播。电子吸收光谱的实时计算需要对电偶极矩进行离散傅里叶变换。光谱分辨率由总传播时间决定，即偶极矩的轨迹长度，这会导致较高的计算成本。我们开发的方法在偶极矩的较短轨迹上使用函数拟合，通过外推实现任意光谱分辨率。数值测试表明，该拟合方法可以通过使用短偶极轨迹来重现高分辨率光谱。对于某些系统，该方法在偶极轨迹短至100原子单位时即可收敛，不过随着光谱密度的增加，收敛难度也会增大。我们还引入了拟合的误差估计，可靠地评估其收敛性，从而评估近似光谱的质量。
