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Retrosynthesis -- the process of identifying a set of reactants to synthesize a target molecule -- is of vital importance to material design and drug discovery. Existing machine learning approaches based on language models and graph neural…

Chemical Physics · Physics 2021-12-10 Ruoxi Sun , Hanjun Dai , Li Li , Steven Kearnes , Bo Dai

The theoretical approach developed here treats uniformly the direct and indirect mechanisms of dissociative recombination (DR) in a diatomic ion. The present theory is based on electron scattering calculations performed at several…

This article solves two major tasks that frequently arise in the theory of electron collisions with a target molecular cation. First, it extends the energy-dependent frame transformation treatment(EDFT), which is needed to map fixed-nuclei…

Chemical Physics · Physics 2025-11-25 David Hvizdos , Roman Curik , Chris H Greene

Context: In the seminal works of Zeldovich et al. (1968) and Peebles (1968), a procedure was outlined to obtain the equation of evolution of the hydrogen fraction without an explicit use of the radiative transfer equation. This procedure is…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-09 Francisco Jiménez Forteza , Juan Betancort Rijo

The article presents an improved theoretical description of dissociative recombination of HCO$^+$ and DCO$^+$ ions with a low energy electron. In the previous theoretical study (Phys. Rev. A {\bf 74}, 032707) on HCO$^+$, the vibrational…

Chemical Physics · Physics 2009-11-13 Nicolas Douguet , Viatcheslav Kokoouline , Chris H. Greene

Dissociative recombination of N$_2$H$^+$ is explored in a two-step theoretical study. In a first step, a diatomic (1D) rough model with frozen NN bond and frozen angles is adopted, in the framework of the multichannel quantum defect theory…

Instrumentation and Methods for Astrophysics · Physics 2023-08-16 J. Zs Mezei , M. A. Ayouz , A. Orbán , A. Abdoulanziz , D. Talbi , D. O. Kashinski , E. Bron , V. Kokoouline , I. F. Schneider

We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is…

Atomic Physics · Physics 2016-06-08 Jens Svensmark , Oleg I. Tolstikhin , Lars Bojer Madsen

The latest molecular data - potential energy curves and Rydberg$/$valence interactions - characterizing the super-excited electronic states of CO are reviewed, in order to provide inputs for the study of their fragmentation dynamics.…

Extended Lagrangian Born-Oppenheimer molecular dynamics based on Kohn-Sham density functional theory is generalized in the limit of vanishing self-consistent field optimization prior to the force evaluations. The equations of motion are…

Chemical Physics · Physics 2015-06-23 Anders M. N. Niklasson , Marc J. Cawkwell

The time development of the reduced density matrix for a quantum oscillator damped by coupling it to an ohmic environment is calculated via an identity of the Debye-Waller form. Results obtained some years ago by Hakim and the author in the…

Quantum Physics · Physics 2015-06-26 Vinay Ambegaokar

A nonperturbative electron transfer rate theory is developed based on the reduced density matrix dynamics, which can be evaluated readily for the Debye solvent model without further approximation. Not only does it recover for reaction rates…

Quantum Physics · Physics 2007-05-23 Ping Han , Rui-Xue Xu , Baiqing Li , Jian Xu , Ping Cui , Yan Mo , YiJing Yan

A general quantum adiabatic theorem with and without the time-dependent orthogonalization is proven, which can be applied to understand the origin of activation energies in chemical reactions. Further proofs are also developed for the…

Strongly Correlated Electrons · Physics 2011-11-03 Andrew Das Arulsamy

We explain why the conventional argument for deriving the time-dependent Born-Oppenheimer approximation is incomplete and review recent mathematical results, which clarify the situation and at the same time provide a systematic scheme for…

Mathematical Physics · Physics 2007-12-31 Gianluca Panati , Herbert Spohn , Stefan Teufel

We present a novel approach to the regression of quantum mechanical energies based on a scattering transform of an intermediate electron density representation. A scattering transform is a deep convolution network computed with a cascade of…

Machine Learning · Computer Science 2016-05-23 Matthew Hirn , Nicolas Poilvert , Stéphane Mallat

A direct numerical algorithm for solving the time-nonlocal non-Markovian master equation in the second Born approximation is introduced and the range of utility of this approximation, and of the Markov approximation, is analyzed for the…

Chemical Physics · Physics 2011-06-30 Navinder Singh , Paul Brumer

By studying the lowest excitations of an exactly solvable one-dimensional molecular model, we show that components of Kohn-Sham ensembles can be used to describe charge transfers. Furthermore, we compute the approximate excitation energies…

Chemical Physics · Physics 2018-05-22 Tim Gould , Leeor Kronik , Stefano Pittalis

The technology of Liquid Argon Time-Projection Chambers (LArTPC) plays a very important role in modern neutrino physics. It allows precise tracking and calorimetry in detectors with very large volume and mass. One important component of…

High Energy Physics - Experiment · Physics 2025-09-19 J. Vences , J. Maneira , C. Vilela

We present a modified Marrone-Treanor model for dissociation with rate parameters derived exclusively from quasiclassical trajectory calculations on ab initio potential energy surfaces. Analysis of the trajectory dataset for reactant O2 and…

Chemical Physics · Physics 2025-10-03 Ross S. Chaudhry , Erik Torres , Thomas E. Schwartzentruber , Graham V. Candler

Theoretical investigation of the dissociative recombination (DR) of NeH+ with low-energy electrons in the regime where the process occurs without direct potential energy curve crossings is presented. The calculations are performed using…

Atomic and Molecular Clusters · Physics 2025-09-09 Riyad Hassaine , Janos Zsolt Mezei , Dahbia Talbi , Jonathan Tennyson , Ioan F. Schneider

While the energy-dependent neutron diffusion equation is widely employed in nuclear engineering, its status as an approximation to the transport equation is not yet completely understood, and several different approximations are in use to…

Computational Physics · Physics 2025-12-22 Gabriele Burgio , Christian Reiter , Stefano Lorenzi