Harjinder Singh
Articles written in Journal of Chemical Sciences
Volume 99 Issue 1-2 August 1987 pp 47-51
On scattering from fractal lattices
Gas-surface scattering is speculated as a meaningful problem for understanding the physics of fractals. Fractal behaviour can be associated with a self-similar geometry on a solid surface. The interaction potential for a gas atom or molecule approaching the lattice depends primarily on local factors but a parametric dependence of the cross-section data on the fractal dimension can be conceived. Such a dependence on the self-similar character of a multi-centred target is more explicit when multiple scattering is included. Application of approximation schemes like the previously developed average wavefunction method to this problem is suggested.
Volume 99 Issue 3 September 1987 pp 207-207 Erratum
Volume 106 Issue 2 April 1994 pp 539-551
Lattice gas automata: A tool for exploring dynamical processes
Harjinder Singh Siddhartha Singh B M Deb
The lattice gas automata (LGA) technique as an alternative to the partial differential equation (PDE) approach for studying dynamical processes, including those in reaction-diffusion systems, is reviewed. The LGA approach gained significance after the simulation of Navier-Stokes equation by Hardy
Volume 118 Issue 1 January 2006 pp 23-35
Sangeeta Saini Harjinder Singh Biman Bagchi
Fluorescence resonance energy transfer (FRET) is a popular tool to study equilibrium and dynamical properties of polymers and biopolymers in condensed phases and is now widely used in conjunction with single molecule spectroscopy. In the data analysis, one usually employs the Förster expression which predicts (l/
Volume 119 Issue 5 September 2007 pp 433-440
Quantum control of vibrational excitations in a heteronuclear diatomic molecule
Sitansh Sharma Purshotam Sharma Harjinder Singh
Optimal control theory is applied to obtain infrared laser pulses for selective vibrational excitation in a heteronuclear diatomic molecule. The problem of finding the optimized field is phrased as a maximization of a cost functional which depends on the laser field. A time dependent Gaussian factor is introduced in the field prior to evaluation of the cost functional for better field shape. Conjugate gradient method$^{21,24}$ is used for optimization of constructed cost functional. At each instant of time, the optimal electric field is calculated and used for the subsequent quantum dynamics, within the dipole approximation. The results are obtained using both Morse potential as well as potential energy obtained using
Volume 119 Issue 5 September 2007 pp 441-447
Controlling dynamics in diatomic systems
Controlling molecular energetics using laser pulses is exemplified for nuclear motion in two different diatomic systems. The problem of finding the optimized field for maximizing a desired quantum dynamical target is formulated using an iterative method. The method is applied for two diatomic systems, HF and OH. The power spectra of the fields and evolution of populations of different vibrational states during transitions are obtained.
Volume 119 Issue 5 September 2007 pp 525-531
Purshotam Sharma Abhijit Mitra Sitansh Sharma Harjinder Singh
The base pairing patterns in RNA structures are more versatile and completely different as compared to DNA. We present here results of
Volume 124 Issue 1 January 2012 pp 99-104
Sitansh Sharma Gabriel G Balint-Kurti Harjinder Singh
Optimal control theory in combination with time-dependent quantum dynamics is employed to design laser pulses which can perform selective vibrational and rotational excitations in a heteronuclear diatomic system. We have applied the conjugate gradient method for the constrained optimization of a suitably designed functional incorporating the desired objectives and constraints. Laser pulses designed for several excitation processes of the $HF$ molecule were able to achieve predefined dynamical goals with almost 100% yield.
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