Searcharxiv⌕ Search

arXiv subjects

Yuta Tanaka

Publications and source records attributed to Yuta Tanaka.

12 recordsLinked to original sources
arXiv2026

Integrable full discretization of the multi-component short pulse equation

We propose a new formulation of the multi-component short pulse (MCSP) equation that includes the coupled complex short pulse (CCSP) equation as a reduction. Using Hirota's bilinear method, we construct its $N$-soliton solutions in Pfaffian form. We then derive integrable semi-discrete and fully discrete analogues of the MCSP equation admitting Pfaffian $N$-soliton solutions. The resulting fully discrete system provides a practical self-adaptive moving mesh scheme for numerical simulations. For the parameter sets considered, numerical simulations demonstrate excellent agreement between the numerical and exact solutions, confirming the robustness and high accuracy of the proposed scheme.

nlin.SI↗
arXiv2026

An integrable semi-discretization of the two-component Hunter-Saxton equation

In this paper, we propose an integrable semi-discretization of the two-component Hunter--Saxton (2-HS) equation, the short-wave limit of the two-component Camassa--Holm (2-CH) equation. At the continuous level, we show that the 2-HS equation can be derived from a new bilinear formulation, distinct from the conventional one in the literature, via a pseudo 2-reduction and a hodograph transformation. For the semi-discrete construction, we first discretize the underlying bilinear equations in the spatial direction. We then impose the pseudo 2-reduction and apply a discrete hodograph transformation to obtain the semi-discrete system in the physical variables. To the best of our knowledge, the resulting system is the first integrable semi-discretization that preserves the two-component structure of the 2-HS equation. We construct the N-soliton solutions of the continuous and semi-discrete systems in Wronskian and Casoratian forms, respectively. The integrability of the semi-discrete system is inherited from the underlying integrable hierarchy and is further verified by a Lax pair.

nlin.SI↗
arXiv2026

Search for high-pressure phases of yttrium via a data assimilation approach

We investigate the distorted face-centered-cubic (dfcc) phase of yttrium (Y) using a data-assimilation-based structure search that combines high-resolution powder x-ray diffraction (XRD) data with machine-learning interatomic potentials. By exploring supercells containing up to 128 atoms, we identify three low-enthalpy phases: the previously reported $I4_1/a$ structure and two additional structures, $Ibam$ and $R\overline{3}$. No data-assimilation-derived structure relaxes to the previously proposed $R\overline{3}m$ phase. Phonon calculations show that $I4_1/a$, $Ibam$, and $R\overline{3}$ are dynamically stable, whereas $R\overline{3}m$ exhibits imaginary modes near the $\Gamma$ point, indicating dynamical instability. Enthalpy calculations using both PBE and r$^{2}$SCAN place the four candidate structures within about 10 meV/atom, indicating a complex energy landscape with multiple competing minima, although $R\overline{3}m$ is consistently highest in enthalpy and r$^{2}$SCAN favors $I4_1/a$ throughout the dfcc pressure range. Rietveld refinements of the powder XRD profile at 60 GPa further narrow the viable structural models to $I4_1/a$ and $Ibam$, both of which reproduce the experimental data better than $R\overline{3}m$ and $R\overline{3}$. Taken together with the energetic ordering and dynamical stability, these results identify $I4_1/a$ as the most plausible structure of the dfcc phase of Y, with $Ibam$ remaining a close competing candidate, particularly toward the high-pressure side of the dfcc region.

cond-mat.mtrl-sci↗
arXiv2026

Matlantis-PFP v8: Universal Machine Learning Interatomic Potential with Better Experimental Agreements via r2SCAN Functional

Universal Machine Learning Interatomic Potentials (uMLIPs) enable atomistic simulations and high-throughput screening at scales far beyond those accessible with density functional theory (DFT). However, most existing uMLIPs are trained on Perdew--Burke--Ernzerhof (PBE) generalized gradient approximation (GGA) data and are therefore fundamentally limited by PBE-level accuracy. In this paper, we argue that better zero-shot predictions versus experiments must be an explicit design target for uMLIPs and present PFP v8, a uMLIP available on the Matlantis service that overcomes the inherent limitations of the PBE functional by being trained to reproduce the regularized-restored strongly constrained and appropriately normed (r2SCAN) meta-GGA potential-energy surface across a wide range of chemical domains. Without requiring domain-specific fine-tuning, PFP v8 delivers systematically improved agreement with experimental data or high-accuracy references for crystals, molecules, and surfaces, outperforming PBE-based DFT calculations. Crucially, in long-time molecular dynamics simulations that are computationally impractical with DFT, PFP v8 predicts melting points with an average error of approximately 130 K, halving the error relative to PBE-trained models. These results establish that uMLIPs can move beyond the limitations of their training approximations and achieve substantially improved agreement with experiment across diverse chemical domains, further narrowing the gap between simulation and reality.

physics.chem-ph↗
arXiv2026

Impact of Local Descriptors Derived from Machine Learning Potentials in Graph Neural Networks for Molecular Property Prediction

In this study, we present a framework aimed at enhancing molecular property prediction through the integration of local descriptors obtained from large-scale pretrained machine learning potentials into three-dimensional graph neural networks (3D GNNs). As an illustration, we developed an EGNN-PFP model by integrating descriptors derived from the preferred potential (PFP) features, acquired through Matlantis, into an equivariant graph neural network (EGNN), and evaluated its effectiveness. When tested on the QM9 dataset, comprising small organic molecules, the proposed model demonstrated superior accuracy compared to both the original EGNN models and the baseline models without PFP-derived descriptors for 11 out of the 12 molecular properties. Furthermore, when evaluated on the tmQM dataset, which encompasses transition metal complexes, notable enhancements in performance were observed across all five target properties, indicating the significance of the local atomic environment surrounding transition metals. In essence, the proposed methodology is adaptable to any 3D GNN architecture, and further enhancements in prediction accuracy are anticipated when integrated with continually evolving GNN architectures.

physics.chem-ph↗
arXiv2023

Evolutionary search for superconducting phases in the lanthanum-nitrogen-hydrogen system with universal neural network potential

Recently, Grockowiak $\textit{et al.}$ reported "hot superconductivity" in ternary or multinary compounds based on lanthanum hydride [A. D. Grockowiak $\textit{et al.}$, Front. Electron. Mater. $\textbf{2}$, 837651 (2022)]. In this paper, we explored thermodynamically stable phases and superconducting phases in the lanthanum-nitrogen-hydrogen system (La$_{x}$N$_{y}$H$_{1-x-y}$, $0 \leq x \leq 1$, $0 \leq y \leq 1$) at pressure of 20$\,$GP. We rapidly and accurately constructed the formation-enthalpy convex hull using an evolutionary construction scheme based on density functional theory calculations, extracting the candidates for stable and moderately metastable compounds by the universal neural network potential calculations. The convex hull diagram shows that more than fifty compounds emerge as stable and moderately metastable phases in the region of $\Delta H \leq 4.4$$\,$mRy/atom. In particular, the compounds are concentrated on the line of $x = 0.5$ connecting between LaH and LaN. We found that the superconductivity is gradually enhanced due to N doping for LaH and the superconducting critical temperature $T_{\rm c}$ reaches 8.77$\,$K in La$_2$NH with $y = 0.25$. In addition, we predicted that metastable La$_2$NH$_2$ shows the highest $T_{\rm c}$ value, 14.41$\,$K, of all the ternary compounds predicted in this study. These results suggest that it is difficult to obtain the hot superconductivity in the La-H compounds with N at 20$\,$GPa.

cond-mat.supr-con↗
arXiv2023

Microscopic mechanism of ultrashort-pulse laser ablation of metals: a molecular dynamics study incorporating electronic entropy effects

The microscopic mechanism of metal ablation induced by ultrashort laser pulse irradiation is investigated. A two-temperature model scheme combined with molecular dynamics (TTM-MD) is developed to incorporate electronic entropy effects into the simulation of metal ablation while satisfying the energy conservation law. Simulation with the TTM-MD scheme reveals that ultrashort laser pulse irradiation near the ablation threshold causes high-energy ion emission and sub-nanometer depth ablation, as observed experimentally, due to the electronic entropy effect. It is also shown that the electronic entropy effect is also significant in spallation.

cond-mat.mtrl-sci↗
arXiv2022

Integrable discretizations of the SIR model

Structure-preserving discretizations of the SIR model are presented by focusing on the hodograph transformation and the conditions for integrability for their discrete SIR models are given. For those integrable discrete SIR models, we derive their exact solutions as well as conserved quantities. If we choose the parameter appropriately for one of our proposed discrete SIR models, it conserves the conserved quantities of the SIR model. We also investigate an ultradiscretizable discrete SIR model.

nlin.SI↗
arXiv2021

Development of the temperature-dependent interatomic potential for molecular dynamics simulation of metal irradiated with an ultrashort pulse laser

Laser ablation is often explained by a two-temperature model (TTM) with different electron and lattice temperatures. To realize a classical molecular dynamics simulation of the TTM, we propose an extension of the embedded atom method to construct an interatomic potential that is dependent on the electron temperature. This method is applied to copper, and its validity is demonstrated by comparison of several physical properties, such as the energy-volume curve, phonon dispersion, electronic heat capacity, ablation threshold, and mean square displacement of atoms, with those of finite-temperature density functional theory.

cond-mat.mtrl-sci↗
arXiv2019

Max-Plus Generalization of Conway's Game of Life

We propose a max-plus equation which includes Conway's Game of Life (GoL) as a special case. There are some special solutions to the equation which include and unify those to GoL. Moreover, the multi-value extension of GoL is derived from the equation and the behavior of solutions is discussed.

nlin.CG↗
arXiv2017

Possible electronic entropy-driven mechanism for non-thermal ablation of metals

The physical mechanism for metal ablation induced by femtosecond laser irradiation was investigated. Results of calculations based on finite-temperature density functional theory (FTDFT) indicate that condensed copper becomes unstable at high electron temperatures due to an increase of electronic entropy at large volume, where the local density of states near the Fermi energy increases. Based on these results, an electronic entropy-driven (EED) model is proposed to explain metal ablation with a femtosecond laser. In addition, a mathematical model is developed for simulation of the laser ablation, where the effect of the electronic entropy is included. This mathematical model can quantitatively describe the experimental data in the low-laser-fuence region, where the electronic entropy effect is determined to be especially important.

cond-mat.mtrl-sci↗