Astrochemistry

Astrochemistry

Understanding how atoms and simple molecules have assembled into prebiotic species and biochemical building blocks up to the emergence of life in a primitive Earth, and whether this might have happened elsewhere in the Universe is one of the greatest challenges in contemporary science. Modern astrochemistry deals with understanding and modeling the chemistry of the interstellar and planetary medium so as to give a complete account of the origin and abundance of the nearly 200 detected molecules (among which many prebiotic species) through an interplay of astronomical observations, theory- and experiment-based laboratory investigations, and kinetic models of reaction networks. At SMART we use state-of-the-art theoretical and computational methods to predict structural, spectroscopic and reactive properties of astrochemical species.

Computational spectroscopy

The modeling of the interstellar chemistry starts with spectroscopy. Spectroscopic signatures provide the unequivocal proof of the presence of chemical species in the interstellar medium (ISM), which is the starting point for the development of astrochemical and astrophysical models, and for laying the foundations of astrobiology. Spectroscopy also allows physical conditions and column densities to be inferred, thus providing the necessary background for the development of astrochemical models. What we know about the nature of the ISM largely comes from astronomical observations of the rotational transitions of molecules. In recent years many efforts have been put for the development of ground- and space-based observatories which operate at infrared (IR) to mm-wavelengths and are providing a wealth of spectroscopic information with unprecedented accuracy, spectral coverage, resolution and sensitivity. Although a great deal of information can be retrieved from laboratory experiments, even for small molecules uncertainties in the assignment of some spectral features may occur and a survey of the observational data reveals that many detected lines are still unassigned. On the other hand, quantum chemistry (QC) is nowadays able both to provide accurate spectroscopic information that is not hampered by interaction with environment and to explicitly account for interactions with other molecules or with solid organic or inorganic supports (the interstellar dust). In our group we develop and use refined computational protocols for accurately predicting the structural, spectroscopic and thermochemical properties of gas-phase astrochemical species. Our strategy is based on the computation at the highest possible level of equilibrium properties (molecular structures, harmonic frequencies, electronic energies, etc.), with anharmonicity effects accounted for using accurate yet cost-effective models rooted in density functional theory (DFT).

Kinetics and reaction networks

For modeling the complex network of elementary reactions taking place in extraterrestrial objects, a large number of physico-chemical parameters (e.g.: activation energies, barriers, rate constants, reaction enthalpies, adsorption energies) is required. Popular astrochemical databases, such as KIDA and UMIST, collect kinetic parameters for thousands reactions among hundreds of chemical species. However, a survey of the available literature reveals that much information is outdated or still missing at all, and extrapolations of experimental data obtained at different conditions is not warranted to provide reliable results, while analogy with similar systems can lead to completely erroneous conclusions. Of course, since in astrochemical models the products of each elementary process are the reactants of successive steps, a small error on the thermochemical or kinetic data may expand exponentially across the reaction network. Astrochemical synthesis takes place in a very extreme forge: the temperature of the ISM can be as low as a few K and its average number density is on the order of a few atoms per cm-3. Given the difficulty (often impossibility) to perform kinetic laboratory studies in such harsh conditions the development of accurate and efficient computational strategies for kinetic applications is mandatory for retrieving reliable rate constants. In our group we use state-of-the-art theoretical and computational methods to determine the possible formation/disruption pathways of astrochemical species, and compute the related thermochemical and kinetic aspects.

Publications

  • Ceselin G, Tasinato N, Puzzarini C, Pietropolli Charmet A, Stoppa P, Giorgianni S, CP2-, He- and H2-broadening coefficients of SO2 for ν1 band and ground state transitions for astrophysical applications, Journal of Quantitative Spectroscopy and Radiative Transfer, (2017), DOI: 10.1016/j.jqsrt.2017.02.018
  • Skouteris D, Vazart F, Ceccarelli C, Balucani N, Puzzarini C, Barone V, New quantum chemical computations of formamide deuteration support gas-phase formation of this prebiotic molecule, Monthly Notices of the Royal Astronomical Society Letters 468, L1-L5 (2017), DOI: 10.1093/mnrasl/slx012
  • Spada L, Tasinato N, Vazart F, Barone V, Caminati W, Puzzarini C, Non-covalent interactions and internal dynamics in pyridine-ammonia: a combined quantum-chemical and microwave spectroscopy study, Chemistry - A European Journal, (2017), DOI: 10.1002/chem.201606014
  • Gianturco FA, Satta M, Mendolicchio M, Palazzetti F, Piserchia A, Barone V, Wester R, Exploring a chemical route for the formation of stable anions of polyynes [CnH (n = 2, 4)] in molecular clouds, The Astrophysical Journal 830, 2 (2016), DOI: 10.3847/0004-637X/830/1/2
  • Pacifici L, Pastore M, Garcia E, Laganà A, Rampino S, A dynamics investigation of the C + CH+ → C2+ + H reaction on an ab initio bond-order like potential, The Journal of Physical Chemistry A 120, 5125-5135 (2016), DOI: 10.1021/acs.jpca.6b00564
  • Rampino S, Suleimanov YV, Thermal rate coefficients for the astrochemical process C + CH+ → C2+ + H by ring polymer molecular dynamics, The Journal of Physical Chemistry A 120, 9887-9893 (2016), DOI: 10.1021/acs.jpca.6b10592
  • Rampino S, Pastore M, Garcia E, Pacifici L, Laganà A, On the temperature dependence of the rate coefficient of formation of C2+ from C + CH+, Monthly Notices of the Royal Astronomical Society 460, 2368-2375 (2016), DOI: 10.1093/mnras/stw1116
  • Vazart F, Calderini D, Skouteris D, Latouche C, Barone V, State-of-the-art thermochemical and kinetic computations for astrochemical complex organic molecules: formamide formation in cold interstellar clouds as a case study, Journal of Chemical Theory and Computation 12, 5385-5397 (2016), DOI: 10.1021/acs.jctc.6b00379
  • Barone V, Biczysko M, Puzzarini C, Quantum chemistry meets spectroscopy for astrochemistry: increasing complexity toward prebiotic molecules, Accounts of Chemical Research 48, 1413-1422 (2015), DOI: 10.1021/ar5003285
  • Barone V, Latouche C, Skouteris D, Vazart F, Balucani N, Ceccarelli C, Lefloch B, Gas-phase formation of the prebiotic molecule formamide: insights from new quantum computations, Monthly Notices of the Royal Astronomical Society Letters 453, L31-L35 (2015), DOI: 10.1093/mnrasl/slv094
  • Vazart F, Calderini D, Skouteris D, Latouche C, Barone V, Reassessment of the thermodynamic, kinetic, and spectroscopic features of cyanomethanimine derivatives: a full anharmonic perturbative treatment, Journal of Chemical Theory and Computation 11, 1165-1171 (2015), DOI: 10.1021/ct501147a
  • Vazart F, Latouche C, Skouteris D, Balucani N, Barone V, Cyanomethanimine isomers in cold interstellar clouds: insights from electronic structure and kinetic calculations, The Astrophysical Journal 11, 111 (2015), DOI: 10.1088/0004-637X/810/2/111
  • Puzzarini C, Ali A, Biczysko M, Barone V, Accurate spectroscopic characterization of protonated oxirane: A potential prebiotic species in titan's atmosphere , The Astrophysical Journal 792, 118 (2014), DOI: 10.1088/0004-637X/792/2/118
  • Puzzarini C, Biczysko M, Bloino J, Barone V, Accurate spectroscopic characterization of oxirane: A valuable route to its identification in titan's atmosphere and the assignment of unidentified infrared bands, The Astrophysical Journal 785, 197 (2014), DOI: 10.1088/0004-637X/785/2/107
  • Carnimeo I, Puzzarini C, Tasinato N, Stoppa P, Pietropolli Charmet A, Biczysko M, Cappelli C, Barone V, Anharmonic theoretical simulations of infrared spectra of halogenated organic compounds, The Journal of Chemical Physics 139, 074310 (2013), DOI: 10.1063/1.4817401

People

Vincenzo Barone

Professor
Carovana - Director's Office
Scuola Normale Superiore, Pisa
vincenzo.barone@sns.it


Julien Bloino

CNR Researcher
Palazzo D'Ancona - Office 2.14
Scuola Normale Superiore, Pisa
julien.bloino@pi.iccom.cnr.it


Serena Manti

Post Doc
Palazzo D'Ancona - Office 2.6
Scuola Normale Superiore, Pisa
serena.manti@sns.it


Sergio Rampino

Post Doc
Palazzo D'Ancona - Office 2.6
Scuola Normale Superiore, Pisa
sergio.rampino@sns.it


Dimitrios Skouteris

Researcher
Palazzo D'Ancona - Office 2.1
Scuola Normale Superiore, Pisa
dimitrios.skouteris@sns.it


Nicola Tasinato

Researcher
Palazzo D'Ancona - Office 2.9
Scuola Normale Superiore, Pisa
nicola.tasinato@sns.it


Fanny Vazart

PhD student
Palazzo D'Ancona - Office 2.6
Scuola Normale Superiore, Pisa
fanny.vazart@sns.it