A classical reactive potential for molecular clusters of sulphuric acid and water

Investigating the significance of zero-point motion in small molecular clusters of sulphuric acid and water

The nucleation of particles from trace gases in the atmosphere is an important source of cloud condensation nuclei (CCN), and these are vital for the formation of clouds in view of the high supersaturations required for homogeneous water droplet nucleation. The methods of quantum chemistry have increasingly been employed to model nucleation due to their high accuracy and efficiency in calculating configurational energies; and nucleation rates can be obtained from the associated free energies of particle formation. However, even in such advanced approaches, it is typically assumed that the nucl…

Mathematical model for acid water neutralization with anomalous and fast diffusion

In this paper we model the neutralization of an acid solution in which the hydrogen ions are transported according to Cattaneo's diffusion. The latter is a modification of classical Fickian diffusion in which the flux adjusts to the gradient with a positive relaxation time. Accordingly the evolution of the ions concentration is governed by the hyperbolic telegraph equation instead of the classical heat equation. We focus on the specific case of a marble slab reacting with a sulphuric acid solution and we consider a one-dimensional geometry. We show that the problem is multi-scale in time, with…

水中PFAS等离子体氧化的反应性分子动力学方法

Reactive molecular dynamics approach to PFAS plasma oxidation in water

提出基于ReaxFF的反应性分子动力学方案，在温度斜坡下模拟水中PFAS被羟基自由基降解，并识别PFOA与PFOS的反应路径及产物。

多维偏置在加速动力学中的优势：应用于乙酸酸解离常数 $pK_a$ 的计算

Advantages of multi-dimensional biasing in accelerated dynamics: application to the calculation of the acid $pK_a$ for acetic acid

针对 ReaxFF 模拟乙酸去质子化时单一配位数 CV 导致 $K_a$ 随盒子尺寸变化的问题，引入离子距离作为第二 CV，实现多维偏置并提升采样效率、消除尺寸依赖。

Double Proton Transfer in Hydrated Formic Acid Dimer: Interplay of Spatial Symmetry and Solvent-Generated Force on Reactivity

The double proton transfer (DPT) reaction in hydrated formic acid dimer (FAD) is investigated at molecular-level detail. For this, a global and reactive machine learned (ML) potential energy surface (PES) is developed to run extensive (more than 100 ns) mixed ML/MM molecular dynamics (MD) simulations in explicit molecular mechanics (MM) solvent at MP2-quality for the solute. Simulations with fixed - as in a conventional empirical force field - and conformationally fluctuating - as available from the ML-based PES - charge models for FAD shows significant impact on the competition between DPT an…

Conformational analysis of tannic acid: environment effects in electronic and reactivity properties

Polyphenols are natural molecules of crucial importance in many applications, of which tannic acid (TA) is one of the most abundant and established. Most high-value applications require precise control of TA interactions with the system of interest. However, the molecular structure of TA is still not comprehended at the atomic level, of which all electronic and reactivity properties depend. Here, we combine an enhanced sampling global optimization method with density functional theory (DFT)-based calculations to explore the conformational space of TA assisted by unsupervised machine learning v…