Pranab Sarkar
Articles written in Pramana – Journal of Physics
Volume 45 Issue 1 July 1995 pp 47-63
Pranab Sarkar S P Bhattacharyya
Bound state population dynamics in a diatom modelled by an appropriate Morse oscillator with a time-dependent well-depth is investigated perturbatively both in the absence and presence of high intensity radiation. For sinusoidally oscillating well-depth, the population of the
Volume 54 Issue 3 March 2000 pp 385-392 Research Articles
Tunneling through a time-dependent barrier — a numerical study
We present a numerical investigation of quantum mechanical tunneling process in a double well potential with fluctuating barrier. The tunneling probability and rate are calculated for two cases in which (i) the height of the barrier is undergoing harmonic oscillation with frequency
Volume 56 Issue 4 April 2001 pp 537-543 Research Articles
Calculating pure rotational transitions of water molecule with a simple Lanczos method
We have calculated pure rotational transitions of water molecule from a kinetic energy operator (KEO) with the
Volume 60 Issue 3 March 2003 pp 483-490
Momentum densities and Compton profiles of alkali-metal atoms
Pranab Sarkar Anupam Sarkar S N Roy B Talukdar
It is assumed that the dynamics of valence electrons of alkali-metal atoms can be well accounted for by a quantum-defect theoretic model while the core electrons may be supposed to move in a self-consistent field. This model is used to study the momentum properties of atoms from^{3}Li to^{37}Rb. The numerical results obtained for the momentum density, moments of momentum density and Compton profile are found to be in good agreement with the results of more detailed configuration-interaction calculations for the atom^{3}Li. Similar results for^{11}Na,^{19}K and^{37}Rb are compared with the corresponding Hartree-Fock-Roothaan values only, for want of data from other realistic calculations
Volume 68 Issue 3 March 2007 pp 377-387 Research Articles
Aparna Saha Bidhan Chandra Bag Pranab Sarkar
We present a numerical investigation of the tunneling dynamics of a particle moving in a bistable potential with fluctuating barrier which is coupled to a non-integrable classical system and study the interplay between classical chaos and barrier fluctuation in the tunneling dynamics. We found that the coupling of the quantum system with the classical subsystem decreases the tunneling rate irrespective of whether the classical subsystem is regular or chaotic and also irrespective of the fact that whether the barrier fluctuates or not. Presence of classical chaos always enhances the tunneling rate constant. The effect of barrier fluctuation on the tunneling rate in a mixed quantum-classical system is to suppress the tunneling rate. In contrast to the case of regular subsystem, the suppression arising due to barrier fluctuation is more visible when the subsystem is chaotic.
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