Structural, Electronic, and Dynamical Properties of Liquid Water by ab initio Molecular Dynamics based on SCAN Functional within the Canonical Ensemble
采用SCAN元-GGA泛函近似,对正则系综中的液态水进行了从头算分子动力学(AIMD)模拟,并与GGA水平的PBE泛函和包含PBE泛函的Tkatchenko-Scheffler van der Waals(vdW)色散修正的结果进行了系统的比较.我们分析了液态水的各种性质,包括径向分布函数,氧-氧-氧三重态角分布,四面体,氢键,扩散系数,环统计,态密度,带隙和偶极矩。我们发现,扫描功能通常是更准确的比其他两个功能的液态水,不仅捕获的中程VDW相互作用,但也减轻了PBE模拟中规定的过于强大的氢键。我们还比较了基于扫描的AIMD模拟的结果在典型的等温等压合奏。我们的研究结果表明,SCAN提供了一个可靠的描述大多数结构,电子和动力学性质的液态水。
英文摘要:
We perform ab initio molecular dynamics (AIMD) simulation of liquid water in the canonical ensemble at ambient conditions using the SCAN meta-GGA functional approximation, and carry out systematic comparisons with the results obtained from the GGA-level PBE functional, and Tkatchenko-Scheffler van der Waals (vdW) dispersion correction inclusive PBE functional. We analyze various properties of liquid water including radial distribution functions, oxygen-oxygen-oxygen triplet angular distribution, tetrahedrality, hydrogen bonds, diffusion coefficients, ring statistics, density of states, band gaps, and dipole moments. We find that the SCAN functional is generally more accurate than the other two functionals for liquid water by not only capturing the intermediate-range vdW interactions but also mitigating the overly strong hydrogen bonds prescribed in PBE simulations. We also compare the results of SCAN-based AIMD simulations in the canonical and isothermal-isobaric ensembles. Our results suggest that SCAN provides a reliable description for most structural, electronic, and dynamical properties in liquid water.
For the first time, an ab initio molecular dynamics simulation was performed to describe the C$_3$S/water interface. The simulation shows that oxides with favorable environment are protonated at first, creating very stable hydroxide groups. Proton transfers occur between water and silicates, and between water and hydroxides formed upon water dissociation on the surface. The typical lifetime of these events is on the same timescale than interconversion between Eigen and Zundel ions in bulk water. At the very early stage of the hydration encompassed by our simulation, silanol groups are very uns…
Efficient "on-the-fly" calculation of Raman spectra from \textit{ab-initio} molecular dynamics: Application to hydrophobic/hydrophilic solutes in bulk water
Structure and Dynamics of the Instantaneous Water/Vapor Interface Revisited by Path-Integral and Ab-Initio Molecular Dynamics Simulations
通过路径积分和第二代Car-Parrinello从头算分子动力学模拟结合瞬时表面定义重新审视水/蒸汽界面的结构和动力学[A. P. Willard和D. Chandler,J.Phys.Chem.B114,1954(2010)]。与之前的研究一致,我们发现最顶层水分子的一个OH键从水中指向汽相,而下层的方向则相反。在它们之间,检测到另外的水层,其中分子平行于瞬时水面排列。
Aided by a neural network representation of the density functional theory (DFT) potential energy landscape of water in the RPBE approximation corrected for dispersion, we calculate several structural and thermodynamic properties of its liquid/vapor interface. The neural network speed allows us to bridge the size and time scale gaps required to sample the properties of water along its liquid/vapor coexistence line with unprecedented precision.
Using a monomer potential energy surface to perform approximate path integral molecular dynamics simulation of ab-initio water with near-zero added cost
Knowledge of the electronic stopping curve for swift ions, $S_e(v)$, particularly around the Bragg peak, is important for understanding radiation damage. Experimentally, however, the determination of such feature for light ions is very challenging, especially in disordered systems such as liquid water and biological tissue. Recent developments in real-time time-dependent density functional theory (rt-TDDFT) have enabled the calculation of $S_e(v)$ along nm-sized trajectories. However, it is still a challenge to obtain a meaningful statistically averaged $S_e(v)$ that can be compared to observa…
Ab initio theory of Cr$_2$O$_3$ surface chemistry in solution
使用一种新形式的密度泛函理论的{ \em从头算}描述的电子系统与介电环境接触,我们提出了第一个详细的研究的影响,溶剂对表面化学的Cr $_2$ O $_3$,不锈钢合金的钝化层。与真空相比,我们预测水的存在对氯离子吸附到氧封端表面的影响很小,但对氢与该表面的结合有显著影响。这些结果表明,水的介电屏蔽性能是重要的氧终止表面的钝化效果。
Ab initio studies of ionization potentials of hydrated hydroxide and hydronium
用多体方法计算了氢氧化物和水合氢离子的电离势分布,电子激发构型由{ \it ab initio}分子动力学产生。实验结果得到了很好的再现,并与分子激发态密切相关。在稳定构型中,电离势主要受第一溶剂化层内水分子的扰动。另一方面,在质子转移过程中,电子激发在质子接收复合物和质子供给复合物上都是离域的,这使得两种水合离子的激发能发生移动,光谱变宽。
We report on an extensive study of the viscosity of liquid water at near-ambient conditions, performed within the Green-Kubo theory of linear response and equilibrium ab initio molecular dynamics (AIMD), based on density-functional theory (DFT). In order to cope with the long simulation times necessary to achieve an acceptable statistical accuracy, our ab initio approach is enhanced with deep-neural-network potentials (NNP). This approach is first validated against AIMD results, obtained by using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional and paying careful attention to c…
Modelling the inelastic scattering of electrons in water is fundamental, given their crucial role in biological damage. In Monte Carlo track-structure codes used to assess biological damage, the energy loss function, from which cross sections are extracted, is derived from different semi-empirical optical models. Only recently, first ab-initio results for the energy loss function and cross-sections in water became available. For benchmarking purpose, in this work, we present ab-initio linear-response time-dependent density functional theory calculations of the energy loss function of liquid wa…
Despite great efforts over the past 50 years, the simulation of water still presents significant challenges and open questions. At room temperature and pressure, the collective molecular interactions and dynamics of water molecules may form local structural arrangements that are non-trivial to classify. Here we employ a data-driven approach built on Smooth Overlap of Atomic Position (SOAP) that allow us to compare and classify how widely used classical models represent liquid water. Macroscopically, the obtained results are rationalized based on water thermodynamic observables. Microscopically…
The nanometric track-structure of energetic ion beams in biological media determines the direct physical damage to living cells, which is one of the main responsibles of their killing or inactivation during radiotherapy treatments or under cosmic radiation bombardment. In the present work, detailed track-structure Monte Carlo simulations, performed with the code SEED (Secondary Electron Energy Deposition), are presented for carbon ions in a wide energy range in liquid water. Liquid water is the main constituent of biological tissues, and carbon ions are one of the most promising projectiles cu…