arXiv subjects

Olga V. Konevtsova

Publications and source records attributed to Olga V. Konevtsova.

3 recordsLinked to original sources

arXiv2026

Nonequilibrium assembly of Lennard-Jones particles on a sphere

Studying physical mechanisms and common geometric principles underlying known spherical packings is crucial for rational design of synthetic nanocontainers. Here we model the growth of small spherical shells containing n<72 identical particles that have their own curvature and interact with each other via the Lennard-Jones potential. The shell assembly is assumed to be nonequilibrium and sequential: at each step, a new particle is attached to the most energetically favorable position, after which the system relaxes. Along with well-known structures of the smallest icosahedral viral protein shells, the proposed mechanism generates a wide range of shells exhibiting square-triangular surface order. Most of such shells are the models of synthetic or natural protein complexes that have octahedral or tetrahedral symmetries and perform various functions. We compare the obtained structures with those resulting from the equilibrium assembly and corresponding to global energy minima. Also, we consider the temperature-dependent stochastic assembly and use the double-minimum Lennard-Jones-Gauss potential to mimic anisotropic particle interactions.

cond-mat.soft↗

arXiv2025

Flat quasicrystalline tilings in terms of density wave approach

Classical Landau theory considers structural phase transitions and crystallization as a condensation of several critical density waves whose wave vectors are symmetrically equivalent. Analyzing the simplest nonequilibrium Landau potentials obtained for decagonal and dodecagonal cases, we derive constraints on the phases of the critical waves and deduce two pairs of flat tilings that are the simplest from the viewpoint of our theory. Each pair corresponds to the same irreducible interference pattern: the vertices of the first and second tilings are located at its minima and maxima, respectively. The first decagonal pair consists of the Penrose P1 tiling and the Tie and Navette one. The second pair is represented by dodecagonal tiling of squares, triangles, and shields, and previously unidentified one formed by regular dodecagons and identical deformed pentagons. Surprisingly, the proposed method for finding extrema of interference patterns provides a straightforward way to generate the Penrose tiling P3 and its more complicated analogues with 2n-fold symmetries. Within Landau theory, we discuss the assembly of the square-triangular tiling and its relationship with the dodecagonal tiling that includes shields. Then we develop a nonequilibrium assembly approach that is based on Landau theory and allows us to produce tilings with random phason strain characteristic of quasicrystals. Interestingly, the approach can generate tilings without or with a minimum number of defective tiles. Examples of real systems rationalized within Landau theory are considered as well. Finally, the derivation of other tilings arising from the reducible interference patterns is discussed, and the relative complexity of non-phenomenological interactions required for the assembly of decagonal and dodecagonal structures is analyzed.

cond-mat.soft↗

arXiv2025

Anomalous proteinaceous shells with octagonal local order

Proteinaceous shells useful for various biomedical applications exhibit a wide range of anomalous structures that are fundamentally different from icosahedral viral capsids described by the Caspar-Klug paradigmatic model. Exploring the Protein Data Bank, we have identified nine different types of anomalous shells structurally close to flat octagonal quasicrystals. As we show, these numerous shells have cubic nets cut from short-period approximants of an octagonal tiling composed of square and rhombic tiles. The approximants and parent tiling are easily obtained within the Landau density wave approach, while the nonequilibrium assembly of them can be simulated using the pair potentials derived from critical density waves. Gluing a polyhedron net and mapping it onto a spherical surface induces tile distortions, and to reduce them, we introduce and minimize the effective elastic energy of the system. Thus, we return quasi-equivalence to previously equivalent tiles. Possible cubic faceting of the octagonal spherical tilings is discussed in terms of the topological charge distribution over the tiling vertices. The proposed structural models describe numerous proteinaceous shells including about half of the known symmetrical enzymes. Our results constitute a fundamental basis for further applications of identified octagonal assemblies and can help to discover and study similar systems in the future.

cond-mat.soft↗