Toward the Understanding of Stress-Induced Mineral Dissolution via Molecular Scale Simulations

Abstract

Stress-induced mineral dissolution at contacts is a critical geophysical process in a broad spectrum of phenomena such as earthquake slip weakening, petroleum migration, and rock deformation. However, there is limited understanding of how this geophysical process originates from the grain-to-grain contacts on a nanoscale. In this study, we simulated the contact process of two quartz asperities in water and present a specially designed molecular dynamics (MD)-based scheme to quantify the dissolution tendency at contacts. Our results suggest that a water layer between the two asperities persists even when the quartz crystals are highly deformed. The MD simulation allowed us to evaluate the thermodynamic activity of the formation of silica species in the solution near the quartz surface. Different from the fact that minerals dissolve significantly at contacts, the finding indicates that only a small region of the contact area adjacent to the center of contacts dissolves first.

Thermo-osmosis in hydrophilic nanochannels: mechanism and size effect

“…Due to the discontinuity of the bulk α-quartz structure at the quartz-water interface, the under-coordinated surface oxygen (O) and silicon (Si) atoms are capped with hydrogen (H) or hydroxyl (OH) groups as in previous studies. 30,56,57 Simulations are conducted in the NVT ensemble with a 1.0 fs time step, and the long-range coulombic (electrostatic) interactions are resolved by the particle-particle and particle-mesh (PPPM) method 58 and temperature is controlled by a canonical sampling thermostat that uses global velocity rescaling with Hamiltonian dynamics. 59 Regarding the force field, ClayFF, parameterized by Cygan et al 60 for describing the interaction of clays with water, is adopted to describe the quartz-water system in our simulations and the flexible single point charge (SPC) 61,62 water model is used in this forcefield.…”

Capillary bridges between unsaturated nano-mineral particles: a molecular dynamics study

“…Moreover, to investigate the adhesive force with regard to the nanostructure of the capillary bridges, we visualised the nanostructure of the bridges by quantifying the distribution of water molecules using the concept of Boltzmann distribution. 29 The distribution of water molecules was treated in the probabilistic sense of potential energy, given by the equation below:where p is the probability of a system being in a certain state, ε is the energy of that state, k is the Boltzmann's constant and T is the thermodynamic temperature.…”

Thermo-osmosis in silica nanochannels

“…1 was used to determine the thermo-osmotic coefficient in a nanochannel of width 𝐿 𝑧 sandwiched between two quartz plates. The crystal structure of α-quartz (Skelton et al, 2011, Du et al, 2018, Ouyang et al, 2020 was used to construct the nanochannels, which was filled with water molecules. Periodic boundary conditions were applied in x and y directions.…”