Pinning the most stable H x C y O z isomers in space by means of high-level theoretical procedures

a b s t r a c t It has been recently demonstrated that there is a high statistical correlation between the relative energies of isomers and their relative abundances in the interstellar medium (ISM). In the present work we use the high-level W2-F12 thermochemical protocol to obtain accurate isomerization energies for a set of 109 H x C y O z isomers, 18 of which have been observed in the ISM so far. We use our benchmark isomerization energies to (i) rationalize the presence of the isomers that have been detected, and (ii) predict which new isomers are likely to be detected in the future. We find that the energetically most stable isomers of H 2 C 3 O (1,2-propadien-1-one), H 8 C 3 O (2-propanol), and H 6 C 3 O 2 (propanoic acid) have not been observed, despite the fact that higher-energy isomers of these chemical formulas have been detected in the ISM. The dipole moments of these isomers are sufficiently large that these species should be observed using microwave spectroscopy techniques

Computational Chemistry and Chemical reactivity

International audienceComputational Chemistry and Chemical reactivit

The multi-scale approaches of theoretical chemistry to understand the molecular complexity of the Interstellar medium

International audienceThe multi-scale approaches of theoretical chemistry to understand the molecular complexity of the Interstellar mediu

The exotic chemistry of space : how theoretical chemistry can help

International audienceAlmost 200 molecules have been detected so far in the interstellar medium and circumstellar shells among which 60 are organic compounds with more than 6 atoms with a straight-chain backbone. Understanding the formation and destruction paths of these molecules both in the gas-phase and in/on solids (cosmic grains, ices) is crucial to diagnose the physical condition of the environments where this chemistry take place. There is therefore a strong demand from the astrophysical community for its study and theoretical chemistry had become an important tool for such a task specially when experiments are not possible because of the unstable species involved (radicals, ions) or because of the extreme conditions of temperature

Contribution a l'etude theorique des reactions de recombinaison dissociative des ions formyle et thioformyle

SIGLECNRS T 58769 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Theoretical approaches for gas-phase and ice surfaceprocesses

International audienceIt is nowadays an evidence that both gas phase reactive collisions and heterogeneous chemistry involving interstellar grains/ices, play a fundamental role in the formation ofmolecules in space. For the last processes, in addition to understanding the catalytic role of the solid phase, there is also the problem of understanding the adsorption, diffusion anddesorption of the reactants and/or products as well as the thermal exchanges between the products and the solid phase. Theoretical chemistry is able to address both chemistries withmore or less accuracy and success but always bringing useful information for astrochemical modelling. I will through this talk , try to address in a manner accessible to an interdisciplinary audience, the approaches used by the theoretical chemists/physicists of the PCMI community to understand both this gas phase and solid state chemistry

How to obtain the potential energy surfaces governing the dissociative recombination of molecular ions with electrons

International audienceHow to obtain the potential energy surfaces governing the dissociative recombination of molecular ions with electron

Theoretical Chemistry for Astrochemistry

International audienceAlmost 200 molecules have been detected so far in the interstellar medium and circumstellar shells among which 60 are organic compounds with more than 6 atoms with a straight-chain backbone. Understanding the formation and destruction paths of these molecules both in the gas-phase and in/on solids (cosmic grains, ices) is crucial to diagnose the physical condition of the environments where this chemistry take place. There is therefore a strong demand from the astrophysical community for its study and theoretical chemistry had become an important tool for such a task specially when experiments are not possible because of the unstable species involved (radicals, ions) or because of the extreme conditions of temperatures (10-100K) and densities (102-108 particles/cm3) to be considered and not always reproducible in the laboratory. To illustrate the role of theoretical chemistry in understanding space chemistry I will present few theoretical studies that have elucidated astrochemical problem

The exotic chemistry of space : how theoretical chemistry can help

International audienceAlmost 200 molecules have been detected so far in the interstellar medium and circumstellar shells among which 60 are organic compounds with more than 6 atoms with a straight-chain backbone. Understanding the formation and destruction paths of these molecules both in the gas-phase and in/on solids (cosmic grains, ices) is crucial to diagnose the physical condition of the environments where this chemistry take place. There is therefore a strong demand from the astrophysical community for its study and theoretical chemistry had become an important tool for such a task specially when experiments are not possible because of the unstable species involved (radicals, ions) or because of the extreme conditions of temperature

Theoretical studies on polyphenyls

International audienceIR spectra of polyphenyls calculated using methods of quantum chemistry are presented