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A model in which a projectile like fragment can be simply regarded as a remnant after removal of some part of the projectile leads to an excited fragment. This excitation energy can be calculated with a Hamiltonian that gives correct…

Nuclear Theory · Physics 2015-06-15 S. Das Gupta , S. Mallik , G. Chaudhuri

The availability of collisional rate coefficients with H$_2$ is a pre-requisite for interpretation of observations of molecules whose energy levels are populated under non local thermodynamical equilibrium conditions. In the current study,…

Astrophysics of Galaxies · Physics 2015-06-22 F. Daniel , A. Faure , L. Wiesenfeld , E. Roueff , D. C. Lis , P. Hily-Blant

A method for integrating the chemical equations associated with nuclear combustion at high temperature is presented and extensively checked. Following the idea of E. M\"uller, the feedback between nuclear rates and temperature was taken…

Astrophysics · Physics 2007-05-23 Ruben M. Cabezon Gomez , Domingo Garcia-Senz , Eduardo Bravo

An artificial neural network (ANN) is investigated as a tool for estimating rate coefficients for the collisional excitation of molecules. The performance of such a tool can be evaluated by testing it on a dataset of collisionally-induced…

Instrumentation and Methods for Astrophysics · Physics 2014-11-20 David A. Neufeld

For the one-dimensional linear kinetic equations with collisional frequency of the molecules, proportional to the module velocity of molecules, analytical solutions of problems about temperature jump and weak evaporation (condensation) in…

Mathematical Physics · Physics 2014-06-10 A. V. Latyshev , A. A. Yushkanov

Water is a key molecule in many astrophysical studies. Its high dipole moment makes this molecule to be subthermally populated under the typical conditions of most astrophysical objects. This motivated the calculation of various sets of…

Astrophysics of Galaxies · Physics 2015-06-11 F. Daniel , J. R. Goicoechea , J. Cernicharo , M. -L. Dubernet , A. Faure

Thermal rate coefficients for some atomic collisions have been observed to be remarkably independent of the details of interatomic interactions at short range. This makes these rate coefficients universal functions of the long-range…

Atomic Physics · Physics 2024-12-20 Xuyang Guo , Kirk W. Madison , James L. Booth , Roman V. Krems

Radiative decay processes at cold and ultra cold temperatures for Sulfur atoms colliding with protons are investigated. The MOLPRO quantum chemistry suite of codes was used to obtain accurate potential energies and transition dipole…

Atomic Physics · Physics 2015-02-26 G Shen , P C Stancil , J G Wang , J F McCann , B M McLaughlin

Motivated by recent observations with Herschel/PACS, and the availability of new rate coefficients for the collisional excitation of CO (Yang et al. 2010), the excitation of warm astrophysical CO is revisited with the use of numerical and…

Astrophysics of Galaxies · Physics 2015-06-04 David A. Neufeld

Collisional excitation rate coefficients play an important role in the dynamics of energy transfer in the interstellar medium. In particular, accurate rotational excitation rates are needed to interpret microwave and infrared observations…

Solar and Stellar Astrophysics · Physics 2015-06-10 Benhui Yang , K. M. Walker , R. C. Forrey , P. C. Stancil , N. Balakrishnan

Rate coefficients for rotational transitions in H_2 induced by H_2 impact are presented. Extensive quantum mechanical coupled-channel calculations based on a recently published (H_2)_2 potential energy surface were performed. The potential…

Rotational transitions in molecular hydrogen collisions are computed. The two most recently developed potential energy surfaces for the H2-H2 system are used from the following works: 1) A.I. Boothroyd, P.G. Martin, W.J. Keogh, M.J.…

Chemical Physics · Physics 2009-11-11 Renat A. Sultanov , Dennis Guster

Quantitative spectroscopy of molecular hydrogen has generated substantial demand, leading to the accumulation of diverse elementary-process data encompassing radiative transitions, electron-impact transitions, predissociations, and…

We discuss a method to calculate with quantum molecular dynamics simulations the rate of energy exchanges between electrons and ions in two-temperature plasmas, liquid metals and hot solids. Promising results from this method were recently…

Computational Physics · Physics 2020-02-05 Jacopo Simoni , Jérôme Daligault

We present a simple method to calculate the binary collision rate between atoms in near-resonant optical lattices. The method is based on the Monte Carlo wave function simulations and the collision rate is obtained by monitoring the quantum…

Atomic Physics · Physics 2009-11-07 Jyrki Piilo

A five-dimensional coupled states (5D-CS) approximation is used to compute cross sections and rate coefficients for CO+H2 collisions. The 5D-CS calculations are benchmarked against accurate six-dimensional close-coupling (6D-CC)…

Instrumentation and Methods for Astrophysics · Physics 2017-01-20 Christina Castro , Kyle Doan , Michael Klemka , Robert C. Forrey , B. H. Yang , Phillip C. Stancil , N. Balakrishnan

Results for quantum mechanical calculations of the integral cross sections and corresponding thermal rate coefficients for para-/ortho-H2+HD collisions are presented. Because of significant astrophysical interest in regard to the cooling of…

Chemical Physics · Physics 2015-05-13 Renat A. Sultanov , Avas V. Khugaev , Dennis Guster

Using a quantum-mechanical close-coupling method, we calculate cross sections for fine structure excitation and relaxation of Si and S atoms in collisions with atomic hydrogen. Rate coefficients are calculated over a range of temperatures…

Atomic Physics · Physics 2024-12-10 Pei-Gen Yan , James F. Babb

The estimation of molecular abundances in interstellar clouds from spectroscopic observations requires radiative transfer calculations, which depend on basic molecular input data. This paper reviews recent developments in the fields of…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Floris van der Tak

Radiative cooling is an important ingredient in hydrodynamical models involving evolution of high temperature plasmas. Unfortunately, calculating an accurate cooling coefficient generally requires the solution of over a hundred differential…

Astrophysics · Physics 2009-11-06 Robert A. Benjamin , Bradford A. Benson , Donald P. Cox