arXiv subjects

Mathias Boström

Publications and source records attributed to Mathias Boström.

At least 19 recordsLinked to original sources

arXiv2026

A mechanism for ice growth on the surface of a spherical water droplet

The formation and growth of ice particles, particularly on the surfaces of spherical water droplets, bear profound implications for localized weather systems and global climate. Herein, we develop a theoretical framework for ice nucleation on minuscule water droplets, establishing that $10\sim5000\rm\ nm$ droplets can considerably increase in volume, making a substantial contribution to ice formation within mist, fog, or even cloud systems. We reveal that the Casimir-Lifshitz (van der Waals) interaction within these systems is robust enough to stimulate both water and ice growth on the surfaces of ice-cold spherical water droplets. The significant impacts and possible detectable phenomena from the curvature are demonstrated.

cond-mat.mtrl-sci↗

arXiv2026

Attractive and repulsive terms in multi-filament dispersion interactions

Filamentary objects such as nano-wires, nanotubes and DNA are of current interest in physics, nanoscience, chemistry, biology and medicine. They can interact via strong, exceptionally long-ranged many-object van der Waals (vdW, dispersion) forces, causing them to cluster into multi-object bundles. We analyse their vdW interactions perturbatively, predicting $N$-object vdW energy contributions that alternate in sign with increasing $N$. Our findings are confirmed here via the first detailed analysis of a 4-cylinder vdW model. We also provide novel insights permitting these tendencies to be understood simply in terms of electronic screening and anti-screening. Our results suggest that a non-perturbative calculation will be required for reliable prediction of dispersion interactions in these ubiquitous systems.

cond-mat.mtrl-sci↗

arXiv2026

"Observations on the possible electromagnetic nature of nucleon interactions and pions" -- historical manuscript from 1969 by B. W. Ninham and C. Pask

This manuscript presents an historical perspective prepared by Barry Ninham and Colin Pask in 1969 on the connection between quantum electrodynamics theory and nucleon interactions. A new theory of strong interactions based on electromagnetic considerations is proposed. Energy and force range magnitudes are correctly given. A new theory of the pion emerges and the pion mass and lifetime are calculated. No strong interaction coupling constant is required.

nucl-th↗

arXiv2026

Prediction of a measurable sign change in the Casimir force using a magnetic fluid

We demonstrate quantum levitation controlled by Casimir forces acting between a polystyrene surface and a Teflon-coated metallic substrate immersed in a mixture of Toluene and magnetite particles. This system experiences repulsion-attraction transitions in the Casimir interaction for distances where the effect is measurable. This Casimir trapping can be controlled by clever choices of metallic and ferrofluid materials, which are directly linked to the emergence of the trapping effect. Thermal and quantum contributions are investigated in detail, showing how the optical and magnetic properties of the ferrofluid and other materials affect the magnitude of the trapping and its distance range of observability.

quant-ph↗

arXiv2025

Dispersion Interaction Between Thin Conducting Cylinders

The ground state and excited state resonance dipole-dipole interaction energy between two elongated conducting molecules are explored. We review the current status for ground state interactions. This interaction is found to be of a much longer range than in the case when the molecules are pointlike and nonconducting. These are well known results found earlier by Davies, Ninham, and Richmond, and later, using a different formalism, by Rubio and co-workers. We show how the theory can be extended to excited state interactions. A characteristic property following from our calculation is that the interaction energy dependence with separation ($R$) goes like $f(R)/R^2$ both for resonance and for the van der Waals case in the long range limit. In some limits $f(R)$ has a logarithmic dependency and in others it takes constant values. We predict an unusual slow decay rate for the energy transfer between conducting molecules.

physics.chem-ph↗

arXiv2025

High-temperature plasma in Casimir physics

We present a short review of an unusual but important application for a high-temperature charged plasma. The unorthodox proposition was made by Ninham concerning a contribution from Casimir forces across high-temperature electron-positron plasma in nuclear interactions. The key message in the current work is how high temperatures ($\sim10^{11}$ \,K) pop out as essential. Clearly, classical, semi-classical, and quantum considerations for the background media impact both the Casimir effect and the physics of stars and the Universe.

cond-mat.mtrl-sci↗

arXiv2025

Exploring the wettability of liquid iron on refractory oxides with sessile drop technique and density-functional derived Hamaker constants

The macroscopic interactions of liquid iron and solid oxides, such as alumina, calcia, magnesia, silica, and zirconia manifest the behavior and efficiency of high-temperature metallurgical processes. The oxides serve dual roles, both as components of refractory materials in submerged entry nozzles and also as significant constituents of non-metallic inclusions in the melt. It is therefore crucial to understand the physicochemical interplay between the liquid and the oxides in order to address the nozzle clogging challenges, and thereby optimize cast iron and steel production. This paper presents a methodology for describing these interactions by combining the materials' dielectric responses, computed within the density functional theory, with the Casimir-Lifshitz dispersion forces to generate the Hamaker constants. The approach provides a comprehensive understanding of the wettability of iron against these refractory oxides, revealing the complex relation between molecular and macroscopic properties. Our theoretically determined crystalline structures are confirmed by room-temperature X-ray diffraction, and the contact angles of liquid iron on the oxides are validated with a sessile drop system at the temperature 1823 K. For comparison, we also present the wettability of the oxides by a liquid tin-bismuth alloy. The findings are essential in advancing the fundamental understanding of interfacial interactions in metallurgical science, and are also pivotal in driving the development of more efficient and reliable steelmaking processes.

cond-mat.mtrl-sci↗

arXiv2021

Self-preserving ice layers on CO2 clathrate particles: implications for Enceladus, Pluto and similar ocean worlds

Under both engineering and natural conditions on Earth and in the Universe, some gas hydrates are found to be stabilised outside their window of thermodynamic stability by the formation of an ice layer-a phenomenon termed self-preservation. Low occupancy surface regions on type I CO2 clathrate structures together with the self-preserving ice layer lead to an effective buoyancy for these structures which restricts the size range of particles that float in the ocean on Enceladus, Pluto and similar oceanic worlds. Our goal here is to investigate the implications of Lifshitz forces and low occupancy surface regions on clathrate structures for their self-preservation through ice layer formation, presenting a plausible model based on multilayer interactions through dispersion forces. We predict that the growth of an ice layer between 0.01 and 0.2 $μ$m thick on CO2 clathrate surfaces depends on the presence of surface regions in the gas hydrates with low occupancy. The effective particle density is estimated delimiting a range of particles that would be buoyant in different oceans. Over geological time, deposition of floating CO2 hydrates could result in the accumulation of kilometre-thick hydrate layers above liquid water reservoirs, and below the water ice crusts of their respective ocean worlds. On Enceladus, destabilisation of near-surface hydrate deposits could lead to increased gas pressures that both drive plumes and entrain stabilised hydrates to be redeposited on the surface of Enceladus or ejected into the E-ring of Saturn. On ocean worlds such as Enceladus and particularly Pluto, the accumulation of thick CO2 hydrate deposits could insulate its ocean against freezing. In preventing the freezing of liquid water reservoirs in ocean worlds, the presence of CO2 hydrate layers could enhance the habitability of ocean worlds in our solar systems and on the exoplanets and exomoons beyond.

astro-ph.EP↗

arXiv2021

Premelting and formation of ice due to Casimir-Lifshitz interactions: Impact of improved parameterization for materials

Recently, the premelting and formation of ice due to the Casimir-Lifshitz interaction, proposed in early 1990s by Elbaum and Schick [Phys. Rev. Lett. 66, 1713-1716 (1991)], have been generalized to diverse practical scenarios, yielding novel physical intuitions and possibilities of application for those phenomena. The properties of materials, in particular, the electrical permittivity and permeability, exert significant influences on the Casimir-Cifshitz energies and forces, and hence on the corresponding premelting and formation of ice. To address these influences in detail and explore the resulting physics, here we revisit and extend the analyses of previous work, with both the dielectric data utilized there and the latest dielectric functions for ice and cold water. While our previous results are rederived, an error there has also been spotted. For the four-layer cases considered by some of us, the existence of stable configurations depending on the initial conditions has been confirmed, and different types of stability corresponding to minima of the Casimir-Lifshitz free energy are demonstrated. As the new dielectric functions for ice and cold water deviate considerably from those used by Elbaum and Schick, their vital impacts on three- and four-layer configurations are therefore being reconsidered.

cond-mat.mtrl-sci↗

arXiv2020

Non-trivial retardation effects in dispersion forces: From anomalous distance dependence to novel traps

In the study of dispersion forces, nonretarded, retarded and thermal asymptotes with their distinct scaling laws are regarded as cornerstone results governing interactions at different separations. Here, we show that when particles interact in a medium, the influence of retardation is qualitatively different, making it necessary to consider the non-monotonous potential in full. We discuss different regimes for several cases and find an anomalous behaviour of the retarded asymptote. It can change sign, and lead to a trapping potential.

cond-mat.mes-hall↗

arXiv2020

Role of zero point energy in promoting ice formation in a spherical drop of water

We demonstrate that the Lifshitz interaction energy (excluding the self-energies of the inner and outer spherical regions) for three concentric spherical dielectric media can be evaluated easily using the immense computation power in recent processors relative to those of a few decades ago. As a prototype, we compute the Lifshitz interaction energy for a spherical shell of water immersed in water vapor of infinite extent while enclosing a spherical ball of ice inside the shell, such that two concentric spherical interfaces are formed: one between solid ice and liquid water and the other between liquid water and gaseous vapor. We evaluate the Lifshitz interaction energy for the above configuration at the triple point of water when the solid, liquid, and gaseous states of water coexist, and, thus, extend the analysis of Elbaum and Schick in Phys. Rev. Lett. 66 (1991) 1713 to spherical configurations. We find that, when the Lifshitz energy contributes dominantly to the total energy of this system, which is often the case when electrostatic interactions are absent, a drop of water surrounded by vapor of infinite extent is not stable at the triple point. This instability, that is a manifestation of the quantum fluctuations in the medium, will promote formation of ice in water, which will then grow in size indefinitely. This is a consequence of the finding here that the Lifshitz energy is minimized for large (micrometer size) radius of the ice ball and small (nanometer size) thickness of the water shell surrounding the ice. These results might be relevant to the formation of hail in thunderclouds. These results are tentative in that the self-energies are omitted; surface tension and nucleation energy are not considered.

cond-mat.mes-hall↗

arXiv2019

Full-spectrum high resolution modeling of the dielectric function of water

In view of the vital role of water in chemical and physical processes, an exact knowledge of its dielectric function over a large frequency range is important. In this article we report on currently available measurements of the dielectric function of water at room temperature (25$^{\circ}$C) across the full electromagnetic spectrum: microwave, IR, UV and X-ray (up to 100 eV). We provide parameterisations of the complex dielectric function of water with two Debye (microwave) oscillators and high resolution of IR and UV/X-ray oscillators. We also report dielectric parameters for ice-cold water with a microwave/IR spectrum measured at $0.4^\circ$C, while taking the UV spectrum from 25$^{\circ}$C (assuming negligible temperature dependence in UV). We illustrate the consequences of the model via calculations of van der Waals interactions of gas molecules near water surfaces, and an assessment of the thickness of water films on ice and ice films on water. In contrast to earlier models of ice-cold water, we predict that a micron-scale layer of ice is stabilised on a bulk water surface. Similarly, the van der Waals interaction promotes complete freezing rather than supporting a thin premelting layer of water on a bulk ice surface. Density-based extrapolation from warm to cold water of the dielectric function at imaginary frequencies is found to be satisfactory in the microwave but poor (40% error) at IR frequencies.

physics.optics↗

arXiv2019

Dispersion forces in inhomogeneous planarly layered media: A one-dimensional model for effective polarisabilities

Dispersion forces such as van der Waals forces between two microscopic particles, the Casimir--Polder forces between a particle and a macroscopic object or the Casimir force between two dielectric objects are well studied in vacuum. However, in realistic situations the interacting objects are often embedded in an environmental medium. Such a solvent influences the induced dipole interaction. With the framework of macroscopic quantum electrodynamics, these interactions are mediated via an exchange of virtual photons. Via this method the impact of a homogeneous solvent medium can be expressed as local-field corrections leading to excess polarisabilities which have previously been derived for hard boundary conditions. In order to develop a more realistic description, we investigate on a one-dimensional analog system illustrating the influence of a continuous dielectric profile.

quant-ph↗

arXiv2019

Dispersion forces stabilise ice coatings at certain gas hydrate interfaces which prevent water wetting

Gas hydrates formed in oceans and permafrost occur in vast quantities on Earth representing both a massive potential fuel source and a large threat in climate forecasts. They have been predicted to be important on other bodies in our solar systems such as Enceladus, a moon of Saturn. CO$_2$-hydrates likely drive the massive gas-rich water plumes seen and sampled by the spacecraft Cassini, and the source of these hydrates is thought to be due to buoyant gas hydrate particles. Dispersion forces cause gas hydrates to be coated in a 3-4 nm thick film of ice, or to contact water directly, depending on which gas they contain. These films are shown to significantly alter the properties of the gas hydrate clusters, for example, whether they float or sink. It is also expected to influence gas hydrate growth and gas leakage.

astro-ph.EP↗

arXiv2018

Fluid sensitive nanoscale switching with quantum levitation controlled by $α$-Sn/$β$-Sn phase transition

We analyse the Lifshitz pressure between silica and tin separated by a liquid mixture of bromobenzene and chlorobenzene. We show that the phase transition from semimetallic $α$-Sn to metallic $β$-Sn can switch Lifshitz forces from repulsive to attractive. This effect is caused by the difference in dielectric functions of $α$-Sn and $β$-Sn, giving both attractive and repulsive contributions to the total Lifshitz pressure at different frequency regions controlled by the composition of the intervening liquid mixture. In this way, one may be able to produce phase transition-controlled quantum levitation in liquid medium.

cond-mat.other↗

arXiv2018

Orientational dependence of the van der Waals interactions for finite-sized particles

Van der Waals forces as interactions between neutral and polarisable particles act at small distances between two objects. Their theoretical origin lies in the electromagnetic interaction between induced dipole moments caused by the vacuum fluctuations of the ground-state electromagnetic field. The resulting theory well describes the experimental situation in the limit of the point dipole assumption. At smaller distances, where the finite size of the particles has to be taken into account, this description fails and has to be corrected by higher orders of the multipole expansion, such as quadrupole moments and so on. With respect to the complexity of the spatial properties of the particles this task requires a considerable effort. In order to describe the van der Waals interaction between such particles, we apply the established method of a spatially spread out polarisability distribution to approximate the higher orders of the multipole expansion. We hence construct an effective theory for effects from anisotropy and finite size on the van der Waals potential.

physics.chem-ph↗

arXiv2018

Distance-dependent sign-reversal in the Casimir-Lifshitz torque

The Casimir-Lifshitz torque between two biaxially polarizable anisotropic planar slabs is shown to exhibit a non-trivial sign-reversal in its rotational sense. The critical distance $a_c$ between the slabs that marks this reversal is characterized by the frequency $ω_c\!\sim \!c/2a_c$ at which the in-planar polarizabilities along the two principal axes are equal. The two materials seek to align their principal axes of polarizabilities in one direction below $a_c$, while above $a_c$ their axes try to align rotated perpendicular relative to their previous minimum energy orientation. The sign-reversal disappears in the nonretarded limit. Our perturbative result, derived for the case when the differences in the relative polarizabilities are small, matches excellently with the exact theory for uniaxial materials. We illustrate our results for black phosphorus and phosphorene.

cond-mat.mes-hall↗

arXiv2017

Effective Polarisability Models

Theories for the effective polarisability of a small particle in a medium are presented using different levels of approximation: we consider the virtual cavity, real cavity and the hard-sphere models as well as a continuous interpolation of the latter two. We present the respective hard-sphere and cavity radii as obtained from density-functional simulations as well as the resulting effective polarisabilities at discrete Matsubara frequencies. This enables us to account for macroscopic media in van der Waals interactions between molecules in water and their Casimir-Polder interaction with an interface.

physics.chem-ph↗