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We present the fifth release of the UMIST Database for Astrochemistry (UDfA). The new reaction network contains 6173 gas-phase reactions, involving 467 species, 47 of which are new to this release. We have updated rate coefficients across…

Solar and Stellar Astrophysics · Physics 2015-06-12 D. McElroy , C. Walsh , A. J. Markwick , M. A. Cordiner , K. Smith , T. J. Millar

With the chemical reaction rate database UMIST95 (Millar et al. 1997) we analyze how uncertainties in rate constants of gas-phase chemical reactions influence the modelling of molecular abundances in the interstellar medium. Random…

Astrophysics · Physics 2009-11-10 A. I. Vasyunin , A. M. Sobolev , D. S. Wiebe , D. A. Semenov

We investigate the potential of numerical algorithms to decipher the kinetic parameters involved in multi-step chemical reactions. To this end we study a dimerization kinetics of protein as a model system. We follow the dimerization…

Biological Physics · Physics 2014-12-24 Srijeeta Talukder , Shrabani Sen , Ralf Metzler , Suman K Banik , Pinaki Chaudhury

A two-body gas-phase reaction rate coefficient can be given by the usual Arrhenius-type formula which depends on temperature. The UMIST Database for Astrochemistry is a widely used database for reaction rate coefficients. They provide…

Astrophysics of Galaxies · Physics 2023-08-08 Gargi Shaw , Gary Ferland , M. Chatzikos

Semi-local DFT methods exhibit significant errors for the phase diagrams of transition-metal oxides that are caused by an incorrect description of molecular oxygen and the large self-interaction error in materials with strongly localized…

Materials Science · Physics 2022-03-29 Nongnuch Artrith , José Antonio Garrido Torres , Alexander Urban , Mark S. Hybertsen

In this paper, we propose a data-driven method to discover multiscale chemical reactions governed by the law of mass action. First, we use a single matrix to represent the stoichiometric coefficients for both the reactants and products in a…

Chemical Physics · Physics 2021-11-24 Juntao Huang , Yizhou Zhou , Wen-An Yong

Nuclear Astrophysics requires the knowledge of reaction rates over a wide range of nuclei and temperatures. In recent calculations the nuclear level density - as an important ingredient to the statistical model (Hauser-Feshbach) - has shown…

Astrophysics · Physics 2009-10-28 T. Rauscher , F. -K. Thielemann , K. -L. Kratz

We present a novel chemical database for gas-phase astrochemistry. Named the KInetic Database for Astrochemistry (KIDA), this database consists of gas-phase reactions with rate coefficients and uncertainties that will be vetted to the…

Parameter fitting of data to a proposed equation almost always consider these parameters as independent variables. Here, the method proposed optimizes an arbitrary number of variables by the minimization of a function of a single variable.…

Chemical Physics · Physics 2010-06-15 Christopher G. Jesudason

This review focuses on nuclear reactions in astrophysics and, more specifically, on reactions with light ions (nucleons and alpha particles) proceeding via the strong interaction. It is intended to present the basic definitions essential…

Nuclear Theory · Physics 2015-03-17 T. Rauscher

Reactive molecular dynamics (MD) simulation is performed using a reactive force field (ReaxFF). To this end, we developed a new method to optimize the ReaxFF parameters based on a machine learning approach. This approach combines the…

Chemical Physics · Physics 2018-12-11 Hiroya Nakata , Shandan Bai

Chemical reactions are often associated with an energy barrier along the reaction pathway which hinders the spontaneity of the reaction. Changing the energy barrier along the reaction pathway allows one to modulate the performance of a…

Computational Physics · Physics 2018-09-26 Sudipta Kundu , Satadeep Bhattacharjee , Seung-Cheol Lee , Manish Jain

Databases of gas and surface chemical reactions are a key tool for scientists working in a wide range of physical sciences. In Astrochemistry, databases of chemical reactions are used as inputs to chemical models to determine the abundances…

Astrophysics of Galaxies · Physics 2021-01-14 Serena Viti , Jonathan Holdship

The inherent behavioral variability exhibited by stochastic biochemical systems makes it a challenging task for human experts to manually analyze them. Computational modeling of such systems helps in investigating and predicting the…

Quantitative Methods · Quantitative Biology 2020-01-14 Arfeen Khalid

Observations of deuterated species are useful in probing the temperature, ionization level, evolutionary stage, chemistry, and thermal history of astrophysical environments. The analysis of data from ALMA and other new telescopes requires…

Solar and Stellar Astrophysics · Physics 2013-10-21 T. Albertsson , D. A. Semenov , A. I. Vasyunin , Th. Henning , E. Herbst

Accurately modeling chemical reactions at the atomistic level requires high-level electronic structure theory due to the presence of unpaired electrons and the need to properly describe bond breaking and making energetics. Commonly used…

A lot of research work has been carried out in fine tuning model parameters to reproduce experimental data for neutron induced reactions. This however is not the case for proton induced reactions where large deviations still exist between…

Nuclear Theory · Physics 2019-12-30 E. Alhassan , D. Rochman , A. Vasiliev , R. M. Bergmann , M. Wohlmuther , A. J. Koning , H. Ferroukhi

We study the identified particle ratios produced at mid-rapidity in heavy ion collisions, along with their correlations with the collision energy. We employ our earlier proposed Unified Statistical Thermal Freeze-out Model (USTFM), which…

High Energy Physics - Phenomenology · Physics 2015-11-18 Inam-ul Bashir , Saeed Uddin

A recently developed model chemistry (jun-Cheap) has been slightly modified and proposed as an effective, reliable and parameter-free scheme for the computation of accurate reaction rates with special reference to astrochemical and…

Chemical Physics · Physics 2021-06-25 Vincenzo Barone , Jacopo Lupi , Zoi Salta , Nicola Tasinato

Theoretical reaction rates in the temperature range 0.01*10^9<=T[K]<=10.*10^9 are calculated in the statistical model (Hauser-Feshbach formalism) for targets with 10<=Z<=83 (Ne to Bi) and for a mass range reaching the neutron and proton…

Astrophysics · Physics 2009-10-31 T. Rauscher , F. -K. Thielemann
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