Charged particle dynamics in singular spacetimes: hydrogenic mapping and curvature-corrected thermodynamics

We analyze the dynamics of charged test particles in a singular, horizonless spacetime arising as the massless limit of a charged wormhole in the Einstein–Maxwell–Scalar (EMS) framework. The geometry, sustained solely by an electric charge $Q$, features an infinite sequence of curvature singularity shells, with the outermost at $r_{\ast }=\frac{2\mathrm{\mid }Q\mathrm{\mid }}{\pi }$ acting as a hard boundary for nonradial motion, while radial trajectories can access it depending on the particle charge-to-mass ratio $\mathrm{\mid }q\mathrm{\mid }\mathrm{/}m$. Exploiting exact first integrals, we construct the effective potential and obtain circular orbit radii, radial epicyclic frequencies, and azimuthal precession rates. In the weak-field limit ($r\gg \mathrm{\mid }Q\mathrm{\mid }$), the motion reduces to a Coulombic system with small curvature-induced retrograde precession. At large radii, the dynamics maps to a hydrogenic system, with curvature corrections inducing perturbative energy shifts. Approaching $r_{\ast }$, the potential diverges, producing hard-wall confinement. Curvature corrections also modify the spectral thermodynamics, raising energies and slightly altering entropy and heat capacity. Our results characterize the transition from Newtonian-like orbits to strongly confined, curvature-dominated dynamics.