Bone Rebecca A, Chung Moses K J, Ponder Jay W, Riccardi Demian, Muzny Chris, Sundararaman Ravishankar, Schwarz Kathleen
Theiss Research, P.O. Box 127, La Jolla, California 92038, USA.
Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899, USA.
J Chem Phys. 2024 Aug 14;161(6). doi: 10.1063/5.0217883.
Simulating the dielectric spectra of solvents requires the nuanced definition of inter- and intra-molecular forces. Non-polarizable force fields, while thoroughly benchmarked for dielectric applications, do not capture all the spectral features of solvents, such as water. Conversely, polarizable force fields have been largely untested in the context of dielectric spectroscopy but include charge and dipole fluctuations that contribute to intermolecular interactions. We benchmark non-polarizable force fields and the polarizable force fields AMOEBA03 and HIPPO for liquid water and find that the polarizable force fields can capture all the experimentally observed spectral features with varying degrees of accuracy. However, the non-polarizable force fields miss at least one peak. To diagnose this deficiency, we decompose the liquid water spectra from polarizable force fields at multiple temperatures into static and induced dipole contributions and find that the peak originates from induced dipole contributions. Broadening our inquiry to other solvents parameterized with the AMOEBA09 force field, we demonstrate good agreement between the experimental and simulated dielectric spectra of methanol and formamide. To produce these spectra, we develop a new computational approach to calculate the dielectric spectrum via the fluctuation dissipation theorem. This method minimizes the error in both the low and high frequency portions of the spectrum, improving the overall accuracy of the simulated spectrum and broadening the computed frequency range.
模拟溶剂的介电谱需要对分子间和分子内作用力进行细致的定义。非极化力场虽然在介电应用方面经过了全面的基准测试，但无法捕捉到溶剂的所有光谱特征，如水的光谱特征。相反，极化力场在介电光谱的背景下基本上未经测试，但包含有助于分子间相互作用的电荷和偶极子波动。我们对液态水的非极化力场以及极化力场AMOEBA03和HIPPO进行了基准测试，发现极化力场能够以不同程度的精度捕捉到所有实验观察到的光谱特征。然而，非极化力场至少遗漏了一个峰。为了诊断这一缺陷，我们将多个温度下极化力场的液态水光谱分解为静态和诱导偶极子贡献，发现该峰源于诱导偶极子贡献。将我们的研究扩展到用AMOEBA09力场参数化的其他溶剂，我们证明了甲醇和甲酰胺的实验和模拟介电谱之间具有良好的一致性。为了生成这些光谱，我们开发了一种新的计算方法，通过涨落耗散定理来计算介电谱。这种方法将光谱低频和高频部分的误差降至最低，提高了模拟光谱的整体精度，并拓宽了计算频率范围。
