Report on the outcomes of a Short-Term Scientific Mission

Action number: CA21101

Grantee name: Sreckovic Vladimir

Details of the STSM

Title: New molecular data for confined molecular systems and astrochemical modelling
Start and end date: 10/08/2023 to 19/08/2023

Description of the work carried out during the STSM

The methods of computational chemistry have become increasingly important in the last decades for the investigation of interaction and dynamics of small molecules enclosed in larger structures. Despite their enormous size, molecular clouds play an important but poorly understood role as confined systems. Due to scattering and absorption of interstellar radiation molecules that are deep inside molecular clouds can avoid photodissociation and/or photoionization. Therefore, it is important to examine not only radiative but also concurrent processes i.e. collisional processes like general chemi-recombination (where one possible channel is electron driven processes involving molecular ions e.g. dissociative recombination). Analysing the investigated rates gives important information about the presence of the molecular ion. Such species and processes are important. For example helium molecular ion He+2 is present in stellar medium, as well as in the chemistry of the early universe. It has been widely studied due to its importance in a relatively low-temperature system. Also, the role of hydrogen and silicon molecular ions in interstellar medium and beyond is undeniable. Access to such molecular data (containing recommended data) relevant to further modelling is now required by the science community.

In the course of STSM, we investigated chemi- recombination processes which involve small molecules

i.e. hydrogen, helium and silicon molecular ions, and provide data useful for characterization of interstellar chemistry. The collisional reactions have been treated by the dipole resonant mechanism. In this characterization, the processes are caused by the dipole part of the electrostatic interaction between

electron and the quasimolecular complex. This method is especially effective when used with the so-called decay approximation.We theoretically calculated new data sets i.e. cross sections and rate coefficients for corresponding processes i.e. species.

During STSM in Timisoara Vladimir Srećković and Nicolina Pop collected existing literature about theoretical and experimental works in this area of research and discussed the outcomes of the aforementioned species’ rate coefficients and cross sections. Also, we compared data with photodissociation ones.

In this phase of collaboration in Timisoara we prepared and converted these chemi- recombination datasets. We created the data model appropriate for the data which is also compatible with the VAMDC schema and converted data from the textual source to the database, tested the infrastructure and services in order to publish the data.

In Timisoara we wrote a draft of the paper for journal Data (open access journal on data in science, CiteScore – Q2 in Information Systems) with results i.e. dataset.

Description of the STSM main achievements and planned follow-up activities

Direct STSM achievement is a new dataset needed for research and modelling of confined systems in astrochemistry. During this STSM in Timisoara we prepared a draft of the paper for journal Data (open access journal on data in science, CiteScore – Q2 in Information Systems) with the results i.e. dataset and with further discussion of the data model. Also, the result of this STSM is the conversion of new molecular datasets in special format ready to be implemented in the BG node, hosted by BG node is a VAMDC database on top of which Python-based NodeSoftware handles web service requests

With Professor Nicolina Pop from the Politehnica University of Timisoarawe we further analyse the datasets and we submitted the abstract to V Meeting on A&M DATA 2023 ( In near future our plan is to write a manuscript for the journal Universe (Q2 open access journal of General Physics and Astrophysics) with extended research and analysis as a follow-up activity.

With Professor Pop, as future work, we intend to calculate and add new species of interest. Also, our future plan is the integration of graphical representation of data and obtaining a simple fitting formula.

This STSM matches following COSY and WG5 keywords / objectives / deliverables:: Creation of a platform for identification of confined molecular systems relevant to astrochemistry; Development of computational tools for the characterization of interstellar chemistry; Accomplishment evaluation of experimental and computational tools; Development of the astro dataset; Providing exchange and collaboration between research groups working on confined molecular systems scattered over many countries and over various scientific areas, including theoretical and experimental groups in the fields of atomic and molecular physics, physical chemistry, biology, material science, and astrochemistry; Promotion of the exchange of knowledge, technical know-how and ideas, as well as establishing longlasting collaborations between academic partners; Publish and present findings in interdisciplinary conferences and high-impact journals.

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