arXiv subjects

Cody L. Covington

Publications and source records attributed to Cody L. Covington.

5 recordsLinked to original sources

arXiv2026

Time-dependent density functional theory study of strong-field laser-induced coulomb explosion of the HCl dimer

We present a channel-resolved interpretation of laser-driven Coulomb explosion of the HCl dimer from an ensemble of trajectories. Three dominant outcomes are identified: a minor three-body channel and two four-body channels (sequential and near-simultaneous dissociation of both molecules). The key result is that pathway selection is strongly correlated with the degree of ionization during the laser interaction, which is in turn strongly modulated by laser-molecule orientation. Higher early-time ionization predisposes the system toward near-simultaneous four-body breakup, whereas lower ionization favors sequential and three-body fragmentation; for low-ionization cases, a fragment-resolved charge metric further differentiates three-body and sequential behavior. These charge-dependent trends consistently map onto experimentally accessible observables: the simultaneous mechanism dominates the high-energy tail of the kinetic energy release (KER) spectrum and populate distinct regions of the emission-angle distributions, while sequential events concentrate at lower KER. Overall, early-time charge evolution provides a unifying explanation for channel branching and for the channel-resolved fragmentation signatures.

physics.chem-ph↗

arXiv2025

Quantum-electrodynamical time-dependent density functional theory description of molecules in optical cavities

A quantum electrodynamical time-dependent density functional theory framework is applied to describe strongly coupled light--matter interactions in cavity environments. The formalism utilizes a tensor product approach, coupling real-space electronic wave functions with Fock space photonic states. Various molecular systems serve as test cases to examine how coupling parameters and cavity frequencies affect molecular geometry, polaritonic spectra, and intermolecular binding.

physics.chem-ph↗

arXiv2025

Ultrafast Relaxation Dynamics of Inner-Shell Vacancies in Hydrated Pyrrole

We employ real-space, real-time time-dependent density functional theory (TDDFT) combined with Ehrenfest dynamics to investigate ultrafast intermolecular relaxation following inner-valence ionization in hydrated pyrrole. This time-dependent approach treats electronic and nuclear motions simultaneously, allowing the description of electronic excitation, charge transfer, ionization, and nuclear motion.When the initial vacancy in the O 2s 1 state is created on the water molecule, the system predominantly undergoes intermolecular Coulombic decay (ICD) and electron-transfer mediated decay (ETMD), accompanied by pronounced charge transfer between pyrrole and water. In contrast, ionization of the pyrrole site for N 2s electron leads to both ICD and Auger decay channels. These results demonstrate that the decay dynamics are strongly governed by the initial vacancy location, offering microscopic insight into intermolecular energy-transfer mechanisms in hydrated molecular systems.

physics.chem-ph↗

arXiv2025

Time-dependent density functional theory investigation of the formation of H$^{3+}$ from alkanes

The formation of H$^{3+}$ from ethane, propane, and butane dications was investigated with time-dependent density-functional theory (TDDFT) simulations. This approach offers the benefit of simultaneously addressing nuclear and electronic dynamics, enabling the investigation of electronic excitation, charge transfer, ionization, and nuclear motion. For each dication we determined the ground-state HOMO, the branching ratios of all dissociation channels, and the mechanism leading to H$^{3+}$. The simulated branching ratios for ethane and propane are similar, while butane is markedly lower. Ethane follows the minimum-energy pathway (MEP) proposed previously; propane forms H$^{3+}$ mainly via H$_2$ roaming. In butane, H$^{3+}$ appears only through the MEP within the present trajectory set; roaming H$_2$ was not observed under the same conditions.

physics.chem-ph↗

arXiv2025

Time-dependent density-functional study of intermolecular Coulombic decay for 2a$_1$ ionized water dimer

A real-space, real-time time-dependent density functional theory (RT-TDDFT) with Ehrenfest dynamics is used to simulate intermolecular Coulombic decay (ICD) processes following the ionization of an inner-valence electron. The approach has the advantage of treating both nuclear and electronic motion simultaneously, allowing for the study of electronic excitation, charge transfer, ionization, and nuclear motion. Using this approach, we investigate the decay process for the 2a$_1$ ionized state of the water dimer. For the 2a$_1$ vacancy in the proton donor water molecule, ICD is observed in our simulations. In addition, we have identified a novel dynamical process: at the initial stage, the proton generally undergoes a back-and-forth motion. Subsequently, the system may evolve along two distinct pathways: in one, no proton transfer occurs; in the other, the proton departs again from its original position and ultimately completes the transfer process. In contrast, when the vacancy resides in the proton acceptor water molecule, no proton transfer occurs, and ICD remains the sole decay channel.

physics.chem-ph↗