Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · 2603.22521

Molecular dynamics study of perchloric acid using the extended Madrid-2019 force field

M. Cruz-Sánchez·S. Blazquez·C. Vega·V. M. Trejos
View original source ↗Read source document ↗Export metadata ↓

Abstract

Perchloric acid (HClO$_4$) is widely used to prepare perchlorate salts with applications in propellants, industry, environmental chemistry, and biology. In this work, we used the intermolecular parameters from the extended Madrid-2019 force field for the perchlorate anion (ClO$_4^-$) and the oxonium cation (H$_3$O$^+$) together with TIP4P/2005 water to model perchloric acid solutions. The force field uses scaled charges of $\pm0.85e$ for monovalent ions and has been widely applied for aqueous ionic systems. We used the model to predict thermodynamic properties [densities and temperatures of maximum in density (TMD)], structural features (ion-water correlations: ion-hydrogen and ion-oxygen), and transport properties (self-diffusion coefficients and viscosity) of perchloric acid solutions at several concentrations. Experimental densities are predicted in excellent agreement up to 10 $m$. We also performed molecular simulations over a wide range of temperatures in order to determine the TMD of perchloric acid at different molalities. Predicted viscosities at 298.15 K and 1 bar are in good agreement with experimental data for concentrations below 4 $m$. Results are discussed in terms of model strengths and limitations.

Explore related subjects

physics.chem-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M. Cruz-Sánchez, S. Blazquez, C. Vega, V. M. Trejos. 2026-03-30. Molecular dynamics study of perchloric acid using the extended Madrid-2019 force field. https://doi.org/10.5488/cmp.29.13601

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Benchmarking Proton Tunneling Splittings with a Wavefunction-Based Double-Well Model: Application to the Formic Acid Dimer

Proton tunneling across hydrogen bonds is a fundamental quantum effect with implications for spectroscopy, catalysis, and biomolecular stability. While state-of-the-art instanton and path-integral methods provide accurate multidimensional tunneling splittings, simplified one-dimensional models remain valuable as conceptual and benchmarking tools. Here we develop a wavefunction-based framework for tunneling splittings using a Cornell-type double-well potential and apply it as a benchmark for hydrogen-bond tunneling. Analytical WKB estimates and numerical finite-difference solutions are compared across a range of barrier parameters, showing consistent agreement. As a test case, we map the formic acid dimer (FAD) barrier onto a quartic double-well model parameterized to reproduce the reported barrier height of $V_b \\approx 2848~\\text{cm}^{-1}$. The resulting tunneling splitting of about $0.037~\\text{cm}^{-1}$ matches the reduced-dimensional calculations of Qu and Bowman. The close agreement between numerical and semiclassical results highlights the pedagogical and diagnostic value of one-dimensional models, while comparison with molecular benchmarks clarifies their limitations relative to full multidimensional quantum treatments.

physics.chem-ph↗
arXiv2026

A Physics-Regularized Neural Network and Kirchhoff Markov Random Field Framework for Inferring Internal Electrochemical States from Operando Spectromicroscopy

Quantitative understanding of coupled reaction-transport dynamics in lithium-ion battery (LIB) composite electrodes is limited by the inaccessibility of key internal electrochemical states. Here we present a physics-integrated, data-driven framework to reconstruct latent states from operando microscopic X-ray absorption fine structure ($μ$ -XAFS) hyperspectral data of LIB cathodes. Normalized-local-lithium-stoichiometry (NLLS) maps derived from Co K-edge spectra are refined using a physics-regularized neural network that enforces spatial continuity and current conservation to resolve ambiguities in the weak-sensitivity region. The reconstructed NLLS dynamics are embedded in a Kirchhoff-based Markov random field incorporating Kirchhoff's laws, Ohm's law, and Butler-Volmer kinetics to infer interfacial current density, ionic current, electrolyte potential, and effective ionic conductivity. Application to electrodes with differential initial electrolyte concentrations reveals distinct reaction-propagation modes that are consistent with a mechanism involving the non-monotonic concentration dependence of electrolyte conductivity. The inferred electrolyte concentration profiles qualitatively resemble the spatially extended concentration changes observed by independent operando X-ray transmission imaging using a 1 M LiAsF$_6$ electrolyte.

physics.chem-ph↗
arXiv2026

Intracavity Photon Statistics from Correlated Molecular Electronic Structure

Quantum optics characterizes light through photon correlations, but ab initio cavity quantum electrodynamics (QED) has only calculated raw field moments at present. In this study, intracavity photon statistics of cavity-coupled molecules are computed from QED coupled-cluster (QED-CCSD-22) densities and validated against exact diagonalization of the Pauli-Fierz Hamiltonian. A change of coordinate origin or dipole convention displaces the ground state coherently, so second-order and higher cumulants of the cavity field are well defined even for molecular ions. The photon subsystem of QED Hartree-Fock is exactly coherent, so the invariant statistics measure electron-photon correlation. The field fluctuations are super-Poissonian, and their degree of second-order coherence is set by the cavity frequency rather than by the coupling strength, falling from 18.5 to 4.9 for H2 as the cavity is detuned from 5 to 20 eV. A parity selection rule makes the sign of the third cumulant a probe of the orientation of the molecular charge asymmetry along the cavity polarization.

physics.chem-ph↗