scholarly journals Insight on Tricalcium Silicate Hydration and Dissolution Mechanism from Molecular Simulations

2015 ◽  
Vol 7 (27) ◽  
pp. 14726-14733 ◽  
Author(s):  
Hegoi Manzano ◽  
Engin Durgun ◽  
Iñigo López-Arbeloa ◽  
Jeffrey C. Grossman
Keyword(s):  
Molecular Simulations ◽  
Tricalcium Silicate ◽  
Dissolution Mechanism

scholarly journals Reactivity of Different Crystalline Surfaces of C3S During Early Hydration by the Atomistic Approach

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1514 ◽  
Author(s):  
K. Salah Uddin ◽  
Bernhard Middendorf
Keyword(s):  
Tricalcium Silicate ◽  
Dissolution Mechanism ◽  
Dissolution Profile ◽  
Reactive Force ◽  
Material Interface ◽  
Early Hydration ◽  
Lower Reactivity ◽  
Cementitious System ◽  
Insight Into ◽  
Crystalline Surfaces

Early hydration of tricalcium silicate (C3S) has received great attention over the years due to the increased use of composite cement with a reduced number of clinker phases, especially the addition of what should be very reactive C3S to guarantee early strength. Although many mechanisms have been proposed, the dissolution of polygonal C3S at the material interface is not yet fully understood. Over the last decade, computational methods have been developed to describe the reaction in the cementitious system. This paper proposes an atomistic insight into the early hydration and the dissolution mechanism of calcium from different crystalline planes of C3S using reactive force field (ReaxFF) combined with metadynamics (metaD). The reactivity and thermodynamic stability of different crystal planes were calculated from the dissolution profile of calcium during hydration at 298 K. The simulation results, clearly describe the higher reactivity of ( 0 1 ¯ 1 ¯ ), (011), (100), and ( 1 ¯ 00 ) surfaces of C3S due to the strong interaction with the water, whereas, the dissolution profile explains the lower reactivity of ( 1 ¯ 1 ¯ 0 ), (110), ( 0 1 ¯ 0 ) and the effect of water tessellation on the (001), (010) planes.

Split the Charge Difference in Two! a Rule of Thumb for Adding Proper Amounts of Ions in MD Simulations

2020 ◽  
Author(s):  
Matías R. Machado ◽  
Sergio Pantano
Keyword(s):  
Molecular Dynamics ◽  
Ionic Strength ◽  
Molecular Simulations ◽  
Md Simulations ◽  
Good Practices ◽  
Rule Of Thumb ◽  
Ionic Concentrations

<p> Despite the relevance of properly setting ionic concentrations in Molecular Dynamics (MD) simulations, methods or practical rules to set ionic strength are scarce and rarely documented. Based on a recently proposed thermodynamics method we provide an accurate rule of thumb to define the electrolytic content in simulation boxes. Extending the use of good practices in setting up MD systems is promptly needed to ensure reproducibility and consistency in molecular simulations.</p>

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

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