A polarizability driven ab initio molecular dynamics approach to stimulating Raman activity: Application to C 20
A polarizability driven ab initio molecular dynamics approach to stimulating Raman activity: Application to C 20
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极化率驱动的从头算分子动力学方法刺激拉曼活性：在 C 20 中的应用
DOI：
10.1080/00268976.2021.1939453
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发表时间：
2021
影响因子：
1.7
通讯作者：
Kaledin, Martina
中科院分区：
文献类型：
--
作者：
Pierre-Jacques, Dominick;Tyler, Ciara;Dyke, Jason;Kaledin, Alexey L.;Kaledin, Martina
我们描述了一种用于探测拉曼主动振动的驱动分子动力学（DMD）方法的新变体。该方法是传统 μ-DMD 公式的扩展，通过将振荡电场与分子的偶极矩 μ 耦合来模拟红外活性，并通过将场调整到共振频率来诱导能量吸收。目前，我们修改上述规定，通过将两个电场（即频率为 ωP 的“泵浦”光子和频率为 ωS 的斯托克斯光子）耦合到分子的极化率张量 α 来调用拉曼活动，频率之差 ω=ωP–ωS 对应于斯托克斯拉曼位移。如果 ω 接近拉曼主动振动频率，则会发生能量吸收。 Varyingω 允许通过轨迹分析来识别和分配所有拉曼主动振动模式，包括非谐校正。我们证明，α-DMD 轨迹只需要全极化张量及其核导数的一个元素，使得该方法非常适合于初始动力学实现。给出并讨论了使用第一原理计算的数值结果，包括 H2O、CH4 和 C20 富勒烯的振动基础、组合带、泛音。
We describe a novel variant of the driven molecular dynamics (DMD) method derived for probing Raman active vibrations. The method is an extension of the conventionalμ-DMD formulation for simulating IR activity by means of coupling an oscillating electric field to the molecule’s dipole moment,μ, and inducing absorption of energy via tuning the field to a resonant frequency. Presently, we modify the above prescription to invoke Raman activity by coupling two electric fields, i.e. a ‘Pump’ photon of frequencyωPand a Stokes photon of frequencyωSto the molecule’s polarizability tensor,α, with the difference in the frequenciesω=ωP–ωScorresponding to the Stokes Raman shift. Ifωis close to a Raman active vibrational frequency, energy absorption ensues. Varyingωallows identifying and assigning all Raman active vibrational modes, including anharmonic corrections, by means of trajectory analysis. We show that only one element of the full polarizability tensor, and its nuclear derivative, is needed for an α-DMD trajectory, making this method well suited forab initiodynamics implementation. Numerical results using first-principles calculations are presented and discussed for the vibrational fundamentals, combination bands, overtones of H2O, CH4, and the C20fullerene.