Shrabani Sen

Bio: Shrabani Sen is an academic researcher from Rammohan College. The author has an hindex of 1, co-authored 2 publications receiving 7 citations.

Enhancing the branching ratios in the dissociation channels for O(16)O(16)O(18) molecule by designing optimum laser pulses: A study using stochastic optimization.

Abstract: We propose a strategy of using a stochastic optimization technique, namely, simulated annealing to design optimum laser pulses (both IR and UV) to achieve greater fluxes along the two dissociating channels (O18 + O16O16 and O16 + O16O18) in O16O16O18 molecule. We show that the integrated fluxes obtained along the targeted dissociating channel is larger with the optimized pulse than with the unoptimized one. The flux ratios are also more impressive with the optimized pulse than with the unoptimized one. We also look at the evolution contours of the wavefunctions along the two channels with time after the actions of both the IR and UV pulses and compare the profiles for unoptimized (initial) and optimized fields for better understanding the results that we achieve. We also report the pulse parameters obtained as well as the final shapes they take.

An adaptive mutation simulated annealing based investigation of Coulombic explosion and identification of dissociation patterns in (CO2)n2+ clusters.

Abstract: In this communication, we would like to discuss the advantages of adaptive mutation simulated annealing (AMSA) over standard simulated annealing (SA) in studying the Coulombic explosion of (CO2)n2+ clusters for n = 20–68, where ‘n’ is the size of the cluster. We have demonstrated how AMSA itself can overcome the predicaments which can arise in conventional SA and carry out the search for better results by adapting the parameters (only when needed) dynamically during the simulations so that the search process can come out of high energy basins and not go astray for better exploration and convergence, respectively. This technique also has in-built properties for getting more than one minimum in a single run. For a (CO2)n2+ cluster system we have found the critical limit to be n = 43, above which the attractive forces between individual units become greater in value than that of the large repulsive forces and the clusters stay intact as the energetically favoured isomers. This result is in good concurrence with earlier studies. Moreover, we have studied the fragmentation patterns for the entire size range and we have found fission type fragmentation as the favoured mechanism nearly for all sizes.

A theoretical study of molecular structure, optical properties and bond activation of energetic compound FOX-7 under intense electric fields

Abstract: Molecular structure, vibrational and electronic absorption spectra, chemical reactivity of energetic compound FOX-7, one of the most widely used explosives, were studied computationally in presence of an electrostatic field of 0.01–0.05 a.u. The C N bond, which usually triggers the decomposition of FOX-7, is shortened/elongated under a parallel/antiparallel field. The C N bond activation energy varies with the external electric field, decreasing remarkably with the field strength in regardless of the field direction. This is attributed to two aspects: the bond weakening by the field parallel to the C N bond and the stabilization effect on the transition-state structure by the field antiparallel to the bond. The variations in the structure and property of FOX-7 under the electric fields were further analyzed with its distributional polarizability, which is dependent on the charge transfer characteristics through the C N bond.

Selective bond dissociation of HOD molecule by optimally designed polychromatic IR+UV pulse: a genetic-algorithm-based study

Abstract: A theoretical investigation of selective bond dissociation of O–H or O–D bond of HOD molecule is carried out by optimally designed electromagnetic field where optimisation is performed by Genetic A...