Structural, spectroscopic and thermodynamic aspects of azide–water clusters: an approach using a conjugated prescription of stochastic and quantum chemical methods

ABSTRACT

In this work, we have used the stochastic search strategy of adaptive mutation simulated annealing (AMSA) as the search tool to explore quantum chemical potential energy to find structures for clusters for n up to 8. The evaluated structures are then further refined at higher levels of theories to get more accurate values of IR frequencies, interaction energy (IE), solvation energy (SE) and vertical detachment energy (VDE). The variations of IE, SE and VDE are also observed and critically discussed to understand the observed trends and their correspondence with experimental findings. In a real experimental scenario, where finite temperature is present, any obtained property will be dictated by contribution from local isomers along with the global one. Keeping this important fact in mind, we have investigated conformational populations of different isomers for the atmospherically relevant temperature range between 200 K and 300 K.

GRAPHICAL ABSTRACT

Keywords:

• Azide–water clusters
• simulated annealing
• adaptive mutation simulated annealing
• molecular clusters
• quantum chemical calculations

Acknowledgements

P.N. thanks Council of Scientific & Industrial Research: Human Resource Development Group, New Delhi, India, for the award of a Senior Research Fellowship [09/028(0938)/2014-EMR-I]. R.R. sincerely acknowledges Indian Institute of Technology, Bombay Powai, Mumbai, India, for granting a Junior Research Fellowship and S.T. thanks Science and Engineering Research Board, Department of Science and Technology, Government of India, for the award of a National Post Doctoral Fellowship [PDF/2017/000233].

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Pulak Naskar  http://orcid.org/0000-0002-1511-8218

Rituparna Roy  http://orcid.org/0000-0002-8844-7901

Srijeeta Talukder  http://orcid.org/0000-0002-3310-2455

Pinaki Chaudhury  http://orcid.org/0000-0002-5192-7338