arXiv subjects

Patrick Ganster

Publications and source records attributed to Patrick Ganster.

4 recordsLinked to original sources

arXiv2024

Atomistic Simulations of Wetting Dynamics of Water Nanodroplets on Nanotextured Titanium: Implications for Medical Implants

The development of high-performance biomedical implants requires a deep understanding of the molecular interactions between water molecules and titanium (Ti) surfaces. In this study, fully atomistic molecular dynamics simulations were used to study the static and dynamic wetting behavior of water nanodroplets on both flat and femtosecond laser-induced nanotextured Ti surfaces. Our findings reveal a clear transition from Wenzel to Cassie-Baxter wetting states as surface roughness increases, significantly affecting droplet spreading. We also observe the damping of nanodroplet vibrations and a roughness-dependent shift toward hydrophobicity, driven by stronger atomic interactions between water molecules and surface atoms. Furthermore, the interaction energy between water droplets and nano-textured Ti surfaces decreases with increasing roughness, reinforcing the observed changes in wettability. The discrepancies observed between classical wetting models and nanoscale behavior emphasize the limitations of current theoretical approaches and the importance of developing more advanced models. This study provides valuable insights into optimizing Ti surface properties for improved implant performance through controlled wettability.

cond-mat.mes-hall↗

arXiv2019

Ab Initio Investigation Of Phosphorus And Hydrogen Co-segregation And Embrittlement In α-fe Twin Boundaries

We propose a new statistical physics model to study equilibrium solute segregation at grain boundaries and the resulting embrittlement effect. This low-temperature expansion model is general and efficient, and its parameters can be obtained from atomistic calculations. It is possible to take into account multiple species, multiple segregation sites with different segregation free energies, account for configurational entropy, grain radius and site competition between solutes. As an example, the model is then applied to the study of phosphorus and hydrogen co-segregation at $\Sigma3$ $109.5°[0\bar{1}1]\{111\}$ twin boundaries in $α$-Fe, using energetic parameters from density-functional theory calculations. We show that P--H interactions may lead to increased P segregation at grain boundaries and cause additional embrittlement compared to the case where P and H are considered separately.

cond-mat.mtrl-sci↗

arXiv2012

Ge condensation under SiGe oxidization: from Molecular Dynamics simulation to one-dimensional analytic modeling

Oxidization of a dilute Si(Ge) alloy is modeled using an original protocol based on molecular dynamics simulation and rules for the oxygen insertions. These rules, deduced from ab-initio calculations, favor the formation of SiO_2 against GeO_2 oxide which leads to segregation of Ge atoms into the alloy during the oxidization front advance. Ge condensation is then observed close to the SiO_2/Ge interface due to the strain induced by oxydization in this region. From the analysis of the simulation process, we propose a one-dimensional description of Ge condensation wich perfectly reproduces the evolution of the Ge concentration during oxidization of the SiGe alloy.

cond-mat.mtrl-sci↗

arXiv2004

Structural properties of a calcium aluminosilicate glass from molecular-dynamics simulations: A finite size effects study

We study a calcium aluminosilicate glass of composition (SiO$_2$)$_{0.67}$-(Al$_2$O$_3$)$_{0.12}$-(CaO)$_{0.21}$ by means of molecular-dynamics (MD) simulations, using a potential made of two-body and three-body interactions. In order to prepare small samples that can subsequently be studied by first-principles, the finite size effects on the liquid dynamics and on the glass structural properties are investigated. We find that finite size effects affect the Si-O-Si and Si-O-Al angular distributions, the first peaks of the Si-O, Al-O and Ca-O pair correlation functions, the Ca coordination and the oxygen atoms environment in the smallest system (100 atoms). We give evidence that these finite size effects can be directly attributed to the use of three-body interactions.

cond-mat.dis-nn↗