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Theory and applications of fluctuating-charge models.

機(jī)譯：波動電荷模型的理論和應(yīng)用。

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Fluctuating-charge models are computationally efficient methods of treating polarization and charge-transfer phenomena in molecular mechanics and classical molecular dynamics simulations. They are also theoretically appealing as they are minimally parameterized, with parameters corresponding to the chemically important concepts of electronegativities and chemical hardness. However, they are known to overestimate charge transfer for widely separated atoms, leading to qualitative errors in the predicted charge distribution and exaggerated electrostatic properties. We present the charge transfer with polarization current equilibration (QTPIE) model, which solves this problem by introducing distance-dependent electronegativities. A graph-theoretic analysis of the topology of charge transfer allows us to relate the fundamental quantities of charge transfer back to the more familiar variables that represent atomic partial charges. This allows us to formulate a unified theoretical framework for fluctuating-charge models and topological charge descriptors. We also demonstrate the important role of charge screening effects in obtaining correct size extensivity in electrostatic properties. Analyzing the spatial symmetries of these properties allows us to shed light on the role of charge conservation in the electronegativity equalization process. Finally, we develop a water model for use in classical molecular dynamics simulations that is capable of treating both polarization and charge transfer phenomena.
機(jī)譯：波動電荷模型是在分子力學(xué)和經(jīng)典分子動力學(xué)模擬中處理極化和電荷轉(zhuǎn)移現(xiàn)象的高效計算方法。從理論上講，它們還具有吸引力，因為它們的參數(shù)最少，其參數(shù)對應(yīng)于電負(fù)性和化學(xué)硬度的化學(xué)重要概念。然而，眾所周知，它們高估了廣泛分離的原子的電荷轉(zhuǎn)移，從而導(dǎo)致預(yù)測的電荷分布和夸張的靜電性能出現(xiàn)定性誤差。我們提出了帶有極化電流平衡（QTPIE）模型的電荷轉(zhuǎn)移，該模型通過引入距離相關(guān)的電負(fù)性解決了這一問題。電荷轉(zhuǎn)移拓?fù)涞膱D論分析使我們能夠?qū)㈦姾赊D(zhuǎn)移的基本量與代表原子部分電荷的更熟悉的變量聯(lián)系起來。這使我們能夠為波動電荷模型和拓?fù)潆姾擅枋龇⒔y(tǒng)一的理論框架。我們還證明了電荷篩選作用在獲得正確的靜電性能尺寸擴(kuò)展性中的重要作用。分析這些性質(zhì)的空間對稱性，使我們能夠闡明電荷守恒在電負(fù)性均衡過程中的作用。最后，我們開發(fā)了一種用于經(jīng)典分子動力學(xué)模擬的水模型，該模型能夠處理極化和電荷轉(zhuǎn)移現(xiàn)象。

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