arXiv subjects

R. Pant

Publications and source records attributed to R. Pant.

4 recordsLinked to original sources

arXiv2026

Electron dynamics mediate the water-carbon {\pi} bond

The intermolecular interaction between a water molecule and the electrons in aromatic {\pi} systems--the water-{\pi} bond--lies at the heart of many chemical processes, yet its properties remain challenging to measure experimentally and model computationally. Infrared spectroscopy of pyrene anions hydrated by a single water molecule reveals vibrational and electronic motions that are often hidden in condensed phase measurements. Results from new machine-learning approaches to potentials and dipole moments show that the electron dynamics of the aromatic {\pi} cloud quench signals from some of water's vibrations and amplify others. The observed interplay between electronic and vibrational motions has general implications for modeling intermolecular interactions between water and aromatic systems in clusters, solutions, and at interfaces.

physics.chem-ph↗

arXiv2020

A measure for adiabatic contributions to quantum transitions

We construct a measure for the adiabatic contribution to quantum transitions in an arbitrary basis, tackling the generic complex case where dynamics is only partially adiabatic, simultaneously populates several eigenstates and transitions between non-eigenstates are of key interest. Our measure is designed to distinguish transitions between basis states that occur due to the adiabatic change of the underlying populated eigenstates from transitions that occur due to beating between several such eigenstates. We demonstrate that the measure can be applied to material or molecular simulations using time-dependent density functional theory, allowing to quantify the relative importance of adiabaticity and thus nuclear motion, for example, in charge or energy transfer.

quant-ph↗

arXiv2020

Excitation Transport in Molecular Aggregates with thermal motion

Molecular aggregates can under certain conditions transport electronic excitation energy over large distances due to dipole-dipole interactions. Here, we explore to what extent thermal motion of entire monomers can guide or enhance this excitation transport. The motion induces changes of aggregate geometry and hence modifies exciton states. Under certain conditions, excitation energy can thus be transported by the aggregate adiabatically, following a certain exciton eigenstate. While such transport is always slower than direct migration through dipole-dipole interactions, we show that transport through motion can yield higher transport efficiencies in the presence of on-site energy disorder than the static counterpart. For this we consider two simple models of molecular motion: (i) longitudinal vibrations of the monomers along the aggregation direction within their inter-molecular binding potential and (ii) torsional motion of planar monomers in a plane orthogonal to the aggregation direction. The parameters and potential shapes used are relevant to dye-molecule aggregates. We employ a quantum-classical method, in which molecules move through simplified classical molecular dynamics, while the excitation transport is treated quantum mechanically using Schr\"odinger's equation. For both models we find parameter regimes in which the motion enhances excitation transport, however these are more realistic for the torsional scenario, due to the limited motional range in a typical Morse type inter-molecular potential. We finally show that the transport enhancement can be linked to adiabatic quantum dynamics. This transport enhancement through adiabatic motion appears a useful resource to combat exciton trapping by disorder.

physics.chem-ph↗

arXiv2017

Fixed point results for a generalized class of simulation functions with applications

In this paper, we consider a wider class of simulation functions and present some coincidence and common fixed point results in metric spaces. Results obtained in this paper extend, generalize and unify some well-known fixed and common fixed point results. Some illustrative examples are presented. We also discuss some applications to system of integral equations and functional equations arising in dynamic programming.

math.FA↗