Department of Chemistry

Permanent URI for this community

http://ssm.ndl.gov.in/handle/123456789/1162

Browse

Browsing Department of Chemistry by Issue Date

Filter results by year or month
Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    A two state model study of photo-detachment dynamics driven by an optimally designed polychromatic field: A simulated annealing based optimisation
    (International Journal of Quantum Chemistry, 2021) Talukder S.;Seal D.;Naskar P.;Chaudhury P.;Ghosh S.
    The surfaces of urn:x-wiley:00207608:media:qua26676:qua26676-math-0001 and F2 are two well separated surfaces modeled by two Morse potentials. In presence of a field, these two surfaces couple and transition from urn:x-wiley:00207608:media:qua26676:qua26676-math-0002 to F2 takes place resulting in the detachment of an electron. We have applied Simulated Annealing (SA) technique to design the polychromatic field which results in ∼ 95% probability of photo detachment (Pd). Also we have designed a field to achieve photo detachment followed by dissociation of FF bond with nearly 38% dissociation probability. F2 being a homo nuclear diatomic molecule, promotion to the continuum states by directly exciting it from its ground vibrational state is an impossibility and our method appears to be a feasible solution if the target is to break the FF bond.
  • No Thumbnail Available
    Item
    Dissociation of HF molecule in position and momentum representation by an optimally controlled polychromatic field: study in the dual space using simulated annealing
    (Molecular Physics, 2022) Seal D.;Naskar P.;Chaudhury P.;Ghosh S.
    Complementarity of position and momentum representation is at the heart of quantum mechanics. Dissociation of diatomic molecule can be investigated and controlled in conventional coordinate space as well as in momentum space. Our objective in this article is to have the control over the dissociation process irrespective of the representation. We have applied Simulated Annealing (SA) technique for the optimisation of the field, where the effective field strength is kept sufficiently low. The optimisation is carried out in both momentum and position representation on with completely different objective function but leading to similar result.
  • No Thumbnail Available
    Item
    Energetics and spectroscopic studies of CNO(-)(H2O)n clusters and the temperature dependencies of the isomers: An approach based on a combined recipe of parallel tempering and quantum chemical methods
    (Journal of Computational Chemistry, 2024) Naskar P.;Talukder S.
    A system associated with several number of weak interactions supports numerous number of stable structures within a narrow range of energy. Often, a deterministic search method fails to locate the global minimum geometry as well as important local minimum isomers for such systems. Therefore, in this work, the stochastic search technique, namely parallel tempering, has been executed on the quantum chemical surface of the system for –8 to generate global minimum as well as several number of local minimum isomers. IR spectrum can act as the fingerprint property for such system to be identified. Thus, IR spectroscopic features have also been included in this work. Vertical detachment energy has also been calculated to obtain clear information about number of water molecules in several spheres around the central anion. In addition, in a real experimental scenario, not only the global but also the local minimum isomers play an important role in determining the average value of a particular physically observable property. Therefore, the relative conformational populations have been determined for all the evaluated structures for the temperature range between 20K and 400K. Further to understand the phase change behavior, the configurational heat capacities have also been calculated for different sizes.