Transcript JOINT CHEMISTRY – DREAMSLab SEMINAR

JOINT CHEMISTRY – DREAMSLab SEMINAR
Date:
Thursday, February 4, 2016
Time:
15.00
Location:
Aula Maria Curie, Palazzo d’Ancona, SNS
Title:
Dynamics and kinetics of the astrochemical process C + CH+ –> C2+ + H
Speaker:
Dr. Sergio Rampino
Istituto di Scienze e Tecnologie Molecolari - Perugia, Consiglio Nazionale delle
Ricerche
Abstract:
in attachment
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DYNAMICS AND KINETICS OF THE ASTROCHEMICAL PROCESS C + CH+ –> C2++ H
Sergio Rampino
Istituto di Scienze e Tecnologie Molecolari - Perugia, Consiglio Nazionale delle Ricerche
[email protected]
We carried out quasi-classical trajectory (QCT) calculations for the C + CH+ –> C2+ + H reaction on
an ad hoc computed high-level ab initio potential energy surface obtained through an optimal
bond-order based configuration-space sampling [1,2]. Thermal rate coefficients at the
temperatures of relevance in cold interstellar clouds were derived and compared with the
assumed, temperature-independent (capture model) estimates publicly available in kinetic
databases KIDA (http://kida.obs.u-bordeaux1.fr/) and UDfA (http://udfa.ajmarkwick.net/). For a
temperature of 10 K the database value overestimates by a factor of two the one obtained by us
(thus improperly enhancing the destruction route of CH+ in astrochemical kinetic models) which is
seen to double in the temperature range 5–300 K with a sharp increase in the first 50 K [3]. The
computed values were fitted via the popular Arrhenius–Kooij formula and best-fitting parameters
to be included in the online mentioned databases are provided. Further investigation shows that
the temperature dependence of the thermal rate coefficient better conforms to the recently
proposed so-called ‘deformed Arrhenius’ law by Aquilanti and Mundim [4,5]. Insights are given
into the detailed microscopic-branching reaction mechanism after checking the accuracy of QCT
results against quantum wavepacket calculations.
References
[1] S. Rampino, JPCA (2015) DOI: 10.1021/acs.jpca.5b10018
[2] L. Pacifici, M. Pastore, E. Garcia, A. Laganà, S. Rampino, JPCA (2016) submitted
[3] S. Rampino, M. Pastore, E. Garcia, L. Pacifici, A. Laganà, MNRAS (2016) submitted
[4] V. Aquilanti, K. C. Mundim, M. Elango, S. Kleijn, T. Kasai, CPL 498, 209-213 (2010)
[5] V. Aquilanti, K. C. Mundim, S. Cavalli, D. De Fazio, A. Aguilar, J. M. Lucas, CP 398, 186-191
(2012)