Micciarelli Marco, Gabas Fabio, Conte Riccardo, Ceotto Michele
Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milano, Italy.
J Chem Phys. 2019 May 14;150(18):184113. doi: 10.1063/1.5096968.
We present a novel approach to calculate molecular infrared (IR) spectra based on semiclassical (SC) molecular dynamics. The main advance from a previous SC method [M. Micciarelli et al. J. Chem. Phys. 149, 064115 (2018)] consists of the possibility to avoid state-to-state calculations making applications to systems characterized by sizable densities of vibrational states feasible. Furthermore, this new method accounts not only for positions and intensities of the several absorption bands which make up the IR spectrum but also for their shapes. We show that accurate SC IR spectra including quantum effects and anharmonicities for both frequencies and intensities can be obtained starting from SC power spectra. The approach is first tested against the water molecule and then applied to the 10-atom glycine amino acid.
我们提出了一种基于半经典（SC）分子动力学计算分子红外（IR）光谱的新方法。与之前的半经典方法[M. Micciarelli等人，《化学物理杂志》149, 064115 (2018)]相比，主要进展在于有可能避免逐态计算，从而使该方法适用于具有相当大振动态密度特征的系统。此外，这种新方法不仅考虑了构成红外光谱的几个吸收带的位置和强度，还考虑了它们的形状。我们表明，从半经典功率谱出发，可以获得包括频率和强度方面的量子效应与非谐性的精确半经典红外光谱。该方法首先针对水分子进行测试，然后应用于10原子的甘氨酸氨基酸。
