Functional Theory-based Molecular Dynamics Research Articles

Anticorrosion potential of domperidone on copper in different concentration of hydrochloric acid solution

The inhibition performance of domperidone on the corrosion of copper in different concentration of HCl solution has been investigated by electrochemical, weight loss, and surface analysis, and theoretical calculation methods. Results indicate that domperidone was found to be an effective inhibitor with the inhibition efficiency as high as 98.5% when the HCl concentration was 0.01 M, and the corrosion rate of copper increased with the increment of HCl concentration from 0.001 to 1 M. The potentiodynamic polarization results revealed that domperidone can be seen as a mixed type inhibitor when the HCl concentration was high (1 and 0.1 M), while it acted as a cathodic inhibitor for copper at low HCl concentrations (0.01 and 0.001 M). The potentiodynamic polarization results revealed that domperidone can be seen as mixed-type or cathodic inhibitor as the HCl concentration changes. Scanning electron microscopy studies indicated the formation of protective films of inhibitor molecule on copper surface. Besides, density functional theory-based quantum chemical calculations and molecular dynamics simulations showed the electronic structure of domperidone and its optimized adsorption configuration on copper surface, which could account for the experimental findings.

The structure of metal-water interface at the potential of zero charge from density functional theory-based molecular dynamics

We simulated a series of transition metal-water interfaces, namely Pt(111), Au(111), Pd(111) and Ag(111), by density functional theory based molecular dynamics, and found some common structural features for the surface water on different transition metal surfaces. Firstly, there exists a pronounced adsorption layer within ∼5 Å distance from metal surfaces, in which three main water species with different orientations (watA, watB-down and watB-up) could be identified. WatA and watB-down show a lower degree of hydrogen bonding, due to their interaction with the metal surface via one of the lone pairs of the oxygen atoms and via one of their H atoms, respectively. While, watB-up has an almost full coordination shell, indicating it not only forms hydrogen bonds in the adsorption layer, but also with the non-surface water. As expected, the honeycomb-like bilayer model used as the starting point of the simulation was destructed into irregular patterns after ∼10 ps of molecular dynamics simulations, and the surface water coverage concomitantly increases from 0.66 ML to ∼0.8 ML.

A method to calculate redox potentials relative to the normal hydrogen electrode in nonaqueous solution by using density functional theory-based molecular dynamics.

We demonstrate the redox potential calculation relative to the normal hydrogen electrode (NHE) in nonaqueous solution using a density functional theory-based molecular dynamics (DFT-MD) simulation. The calculation of the NHE in nonaqueous solution consists of two processes: the first step is the equilibrated simulation for a proton in nonaqueous solution to determine the space for inserting a proton in solution, and the second step is the thermodynamic integration method to calculate the solvation energy of the proton in the nonaqueous solution. In this work, we apply the method for a cation and an anion, i.e., copper(ii)/copper(i) and iodine/iodide in acetonitrile solution, and show that the errors in the calculated redox potential from experiments are within 0.21 V.