Article
Materials Science, Multidisciplinary
M. Marchwiany, M. Matysiak, A. Majhofer, J. Szczytko, A. Twardowski
Summary: Monte Carlo techniques are used to simulate the magnetic properties of chains of identical, spherical, single domain, ferromagnetic nanoparticles with cubic magnetocrystalline anisotropy. The simulations include hysteresis curves, zero field cooled (ZFC) and field cooled (FC) experiments for chains of varying lengths. Anisotropic dipole-dipole interactions between particles lead to differences in the system's response to magnetic fields parallel and perpendicular to the chain, resulting in wasp-waisted hysteresis loops. The study compares chains with different particle sizes to understand the quantitative scale of the phenomena discussed.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2023)
Article
Chemistry, Physical
Philipp Hoellmer, A. C. Maggs, Werner Krauth
Summary: Event-chain Monte Carlo algorithms for hard-disk dipoles in two dimensions are benchmarked for potential applications in modeling water molecules. The rotation dynamics of dipoles are characterized through integrated autocorrelation times of polarization. The non-reversible event-driven ECMC algorithms show significant speedups compared to the Metropolis algorithm, with differences in speed observed among ECMC variants, indicating Newtonian ECMC as a promising solution for overcoming dynamical arrest in dipolar models with Coulomb interactions.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Ivan Zivic, Suncica Elezovic-Hadzic, Dusanka Marcetic
Summary: This study investigates the persistence length of semi-flexible linear polymers using simulations of self-avoiding random walks on different lattices. The results show that the persistence length of polymer chains is linearly related to the chain length, and it is influenced by the stiffness of the polymers.
PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS
(2022)
Article
Engineering, Aerospace
Yabin Wang, Min Xu, Xiaomin An, Zhongxiang Xu, Wei Xu, Enqian Quan
Summary: This paper investigates the aeroelastic effects in trajectory simulation of a rotary rocket with a large slenderness ratio, proposing a computational method based on CFD/CSD/CFM coupling system. The results show that aeroelastic effect can decrease the range and reduce the landing accuracy of the rocket.
AEROSPACE SCIENCE AND TECHNOLOGY
(2021)
Article
Polymer Science
Lianli Deng, Zehua Wang, Bailu Qu, Ying Liu, Wei Qiu, Shaohe Qi
Summary: This study investigates the effects of flexible chain lengths on the properties of rosin-based epoxy resin. It was found that increasing the flexible chain length of the resin monomers enhanced toughness, adhesion, and water resistance while decreasing pencil hardness and heat resistance. However, the lengthening of the curing agents' flexible chains did not significantly affect the resin's performance. Rosin-based resins showed superior adhesion, water resistance, and weatherability compared to commercial petroleum-based epoxy resins, indicating their remarkable durability.
Article
Chemistry, Multidisciplinary
Yogesh Shelke, Fabrizio Camerin, Susana Marin-Aguilar, Ruben W. Verweij, Marjolein Dijkstra, Daniela J. Kraft
Summary: In this study, flexible colloidal molecules with an in situ controllable motion range and bond directionality were created by assembling spherical particles onto cubes functionalized with complementary surface-mobile DNA. The size ratio of the sphere-to-cube varied to obtain colloidal molecules with different coordination numbers, and it was found that they exhibited a constrained range of motion above a critical size ratio. The confinement of the spheres on the surface of the cube and the probability to change facet were quantified, and temperature was identified as an extra control parameter to switch between full and constrained flexibility.
Article
Chemistry, Multidisciplinary
Junjie Chen, Lingyu Meng
Summary: Graphene-based nanomaterials have important applications in thermal rectification, and defects can be used to modulate the temperature dependence of thermal conductivity. A simplified computational method has been developed to determine the rectification coefficient, and structure factors play a noticeable role in the thermal rectification properties.
Article
Chemistry, Multidisciplinary
Junjie Chen, Lingyu Meng
Summary: This study investigates thermally rectifying materials and graphene-based nanostructure thermal rectifiers for controlling heat flux. The results show that nanoscale systems can asymmetrically conduct heat, with a maximum rectification coefficient of about 70%.
Article
Materials Science, Multidisciplinary
Yogeshwar Prasad
Summary: In this study, we performed finite-temperature determinant quantum Monte Carlo simulation to investigate the attractive Hubbard model on a half-filled bilayer square lattice. We studied various single-particle properties and correlations and found the stable phase under specific interaction range. We also mapped out the phase diagram and observed the absence of competing charge density wave order in the bilayer model.
Article
Physics, Fluids & Plasmas
Seher Karakuzu, Benjamin Cohen-Stead, Cristian D. Batista, Steven Johnston, Kipton Barros
Summary: In this study, a class of Hubbard-Stratonovich transformations suitable for quantum Monte Carlo simulations of Hubbard interactions is considered. A tunable parameter p allows for a continuous variation from a discrete Ising auxiliary field (p = infinity) to a compact auxiliary field that couples to electrons sinusoidally (p = 0). Testing on the single-band square and triangular Hubbard models shows that the severity of the sign problem decreases systematically with increasing p. However, selecting a finite p enables continuous sampling methods such as Langevin or Hamiltonian Monte Carlo. The tradeoffs between various simulation methods are explored through numerical benchmarks.
Article
Physics, Fluids & Plasmas
L. S. Ramirez, P. M. Pasinetti, A. J. Ramirez-Pastor
Summary: The random sequential adsorption of extended objects on two-dimensional regular lattices is investigated. The objects are chains formed by occupying adsorption sites on the substrate through a self-avoiding walk. The study focuses on the jamming coverage dependence on lattice connectivity, where the coverage shows a growing behavior with higher connectivity and is higher for tortuous k-mers compared to linear k-mers.
Article
Chemistry, Physical
Geshuo Wang, Zhenning Cai
Summary: This study focuses on the real-time simulation of open quantum systems, using a hybrid method that combines the inchworm method for the spin-boson model and the modular path integral methodology for spin systems. This method can effectively address the numerical sign problem and has been extensively validated through numerical experiments.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Multidisciplinary
Hung V. -T. Nguyen, Yivan Jiang, Somesh Mohapatra, Wencong Wang, Jonathan C. Barnes, Nathan J. Oldenhuis, Kathleen K. Chen, Simon Axelrod, Zhihao Huang, Qixian Chen, Matthew R. Golder, Katherine Young, Dylan Suvlu, Yizhi Shen, Adam P. Willard, Michael J. A. Hore, Rafael Gomez-Bombarelli, Jeremiah A. Johnson
Summary: This study synthesized water-soluble chiral bottlebrush polymers using macromonomers of different rigidity, and discovered that polymers with conformationally flexible mirror image side chains exhibited significant differences in properties compared to those with comparably rigid mirror image side chains. The observations were rationalized by correlating greater conformational freedom with enhanced chiral recognition, providing insights for the design of future biomaterials.
Article
Engineering, Petroleum
F. Cala, E. Nunez, N. Bahamon, J. A. Fuentes
Summary: A comparison was made between uncertainty assessments using the GUM framework and the Monte Carlo method, confirming the adequacy of the GUM method for liquid hydrocarbon measurements with a vertical fixed-top tank and a positive displacement meter. The maximum differences between GUM and MCM uncertainties were found to be within acceptable tolerance levels for both examples.
Article
Optics
Zhe Guang, Patrick Ledwig, Paloma Casteleiro Costa, Caroline Filan, Francisco E. Robles
Summary: Quantitative oblique back-illumination microscopy (qOBM) is an emerging label-free optical imaging technology that enables 3D, tomographic quantitative phase imaging (QPI) with epi-illumination in thick scattering samples. The study presents a robust optimization of a flexible, fiber-optic-based qOBM system, allowing in silico optimization of the phase signal-to-noise-ratio and eliminating the need for experimental optimization.
Article
Chemistry, Physical
Pietro Luigi Muzzeddu, Hidde Derk Vuijk, Hartmut Loewen, Jens-Uwe Sommer, Abhinav Sharma
Summary: This study investigates the effect of activity gradients on active colloidal molecules. The authors found that as the torque increases, the behavior of active chiral dimers switches from antichemotactic to chemotactic. The emergence of chemotaxis is due to the cooperative exploration of an activity gradient by the two particles. Furthermore, the study shows that the dynamics and chemotactic behavior of chiral active particles are generally different from charged Brownian particles under a magnetic field.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Cheng-Wu Li, Dirk Romeis, Markus Koch, Holger Merlitz, Jens-Uwe Sommer
Summary: In this study, polymer brushes grafted onto planar substrates and cylinder surfaces in a poor solvent are investigated using molecular dynamics simulation, self-consistent field theory, and mean-field theory. A unified expression for the mean field free energy for the three geometrical classes is derived. The analysis reveals that chain elasticity becomes relevant at higher grafting densities and concave geometries, while it can be neglected at low grafting densities in poor solvent conditions.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Polymer Science
Toni Mueller, Jens-Uwe Sommer, Michael Lang
Summary: We investigated the formation and elastic properties of tendomer networks with computer simulations. The gel point analysis showed that there is a limit to the number of slide rings per tendomer for network formation. The elastic properties of tendomers are dominated by the phantom contribution to modulus, with deviations from mean field predictions. We found that the modulus can be significantly enhanced by pre-treating in a selective solvent, and deformation of the chains results in a splitting of tendomer units, leading to strain softening.
Article
Polymer Science
Zahra Mohammadyarloo, Jens-Uwe Sommer
Summary: We studied the phase segregation in polymer solutions in the presence of a co-nonsolvent using molecular dynamics simulations. Increasing the amount of co-nonsolvent results in a condensation of the polymer-co-nonsolvent phase, followed by a re-entry behavior at higher concentrations. The conformation statistics of the polymer chains were found to be consistent with the behavior in semidilute solution at the given concentration.
Article
Physics, Multidisciplinary
Erik Kalz, Hidde Derk Vuijk, Iman Abdoli, Jens-Uwe Sommer, Hartmut Loewen, Abhinav Sharma
Summary: It has been discovered that collisions can enhance self-diffusion in odd-diffusive systems, which goes against the common belief. Through analytical predictions and Brownian dynamics simulations, this counterintuitive behavior in the odd-diffusive system has been explained.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Physical
Ankush Checkervarty, Jens-Uwe Sommer, Marco Werner
Summary: The Bond Fluctuation Model (BFM) is a versatile method for simulating polymers, membranes, and soft matter. In this study, an implicit solvent model based on an artificial neural network (NN) was introduced, which was trained with BFM simulation data for single homopolymers in an explicit solvent. It was demonstrated that the NN-based simulations can reproduce the universal properties of polymers under varying solvent conditions.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Polymer Science
Huaisong Yong, Jens-Uwe Sommer
Summary: Despite the early reports on the observation of cononsolvency, its phase-transition mechanism remains under debate. This study comprehensively investigates the phase behaviors of poly(N-isopropylacrylamide) (PNiPAAm) in sulfoxide or sulfone aqueous solutions. It is found that there is a sharp collapse transition of PNiPAAm brushes in sulfoxide but not in sulfone aqueous solutions. The formation of hydrogen bonds between sulfoxide oxygens and amide hydrogens of the polymer chains plays a critical role in regulating the cononsolvency of PNiPAAm.
Article
Chemistry, Physical
I. Abdoli, H. Loewen, J. -U. Sommer, A. Sharma
Summary: Kramers's theory accurately describes the probability of a thermally activated Brownian particle escaping a potential well, with escape time exponentially decreasing as the barrier height increases. In the presence of a charged particle under a Lorentz force due to an external magnetic field, the dynamics slow down. Our study demonstrates that the barrier height can be effectively modified when a charged particle is exposed to a vortex flow. When combined with a magnetic field, the vortex either pushes the particle radially outside or inside, influencing the particle's escape behavior.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Simon Schubotz, Quinn A. Besford, Saghar Nazari, Petra Uhlmann, Eva Bittrich, Jens-Uwe Sommer, Gunter K. Auernhammer
Summary: Polymer brushes, which are polymer chains tethered to substrates, are highly sensitive to adaptation and can undergo changes in swelling, adsorption, and reorientation due to the surrounding liquid or atmosphere. This study analyzes how the atmosphere surrounding an aqueous droplet affects the contact angle on polymer brush surfaces. The use of a coaxial needle allows for reliable measurement of wetting properties even when the droplet and atmosphere are not in equilibrium. It was found that the water contact angle of a sample can be significantly influenced by the composition and humidity of the surrounding atmosphere.
Article
Polymer Science
J. S. Klos, J. Paturej
Summary: The solution structures of complexes composed of a cationic dendrimer, anionic surfactants, and their counterions were studied using molecular dynamics simulations. Depending on the surfactant concentration and hydrophobicity, the system was found to exist in three structural regimes. In the first regime, surfactant molecules were noncooperatively absorbed by the dendrimer, resulting in loosely distributed unimeric surfactants and counterions. In the second regime, hydrophobic attractions between surfactant tails led to the formation of multichain micellar-like aggregates, while the bulk solution consisted of separate unimers. In the third regime, the surfactants formed multichain aggregates both within the dendrimer and in the bulk. The findings provide molecular insights into the self-assembly of supramolecular complexes and controlled absorption of guest surfactant molecules in dendrimer-based host-guest systems.
Article
Multidisciplinary Sciences
Jens Friedrichs, Ralf Helbig, Julia Hilsenbeck, Prithvi Raj Pandey, Jens-Uwe Sommer, Lars David Renner, Tilo Pompe, Carsten Werner
Summary: Control of adhesion is an important phenomenon in living matter, especially in terms of technological translation. We found that entropic repulsion caused by interfacial orientational fluctuations of cholesterol layers restricts protein adsorption and bacterial adhesion. Our insights provide a new perspective on biointerfaces and may guide future material design in the regulation of adhesion.
Article
Chemistry, Physical
Cheng-Wu Li, Holger Merlitz, Jens-Uwe Sommer
Summary: In this study, we used molecular dynamics simulations to investigate the self-organized formation of droplets from a continuous flow of nanoparticles. We found that using a cylindrical channel decorated with a polymer brush in a marginally poor solvent can facilitate this transformation. Our findings contribute to the design of reliable nanofluidic rectification devices.
Article
Multidisciplinary Sciences
Rushikesh Shinde, Jens Uwe Sommer, Hartmut Loewen, Abhinav Sharma
Summary: This study generalizes the Rouse model to investigate the dynamics of a charged dimer in an external magnetic field. Surprisingly, it is found that for a dimer of oppositely charged particles, the magnetic field greatly enhances the dynamics of the dimer center, even exhibiting superballistic behavior. Additionally, the mobility along the dimer's orientation and its rotational diffusion coefficient are reduced by the magnetic field.
Article
Physics, Fluids & Plasmas
Khristine Haydukivska, Viktoria Blavatska, Jaroslaw S. Klos, Jaroslaw Paturej
Summary: This study investigates the influence of arm architecture on the conformational properties of hybrid star-shaped macromolecules called rosette polymers. The results show that the conformation of rosette polymers undergoes compactification with increasing functionality of grafted rings.
Article
Physics, Fluids & Plasmas
J. S. Klos, J. Paturej
Summary: This study investigates the impact of interactions between dendritic polyeclectrolytes and amphiphilic surfactants on the formation of supramolecular complexes through molecular dynamics simulations. It identifies two crucial parameters, surfactant hydrophobicity (e*) and dendrimer generation (G), that govern the association of surfactants within dendrimers. The study finds that the encapsulation process can be either noncooperative or cooperative depending on the values of e* and G. The results provide guidelines for controlled encapsulation of guest molecules in dendrimer-based guest-host complexes.
