Articles written in Pramana – Journal of Physics
Volume 13 Issue 1 July 1979 pp 15-24 Solids
An analytical expression for the phase shift contribution to the internal partition function for the Morse potential is derived by using an approximate Jost function. This function is shown to be a convergent sum. The numerical results obtained for H2 and HCl show the partition function to be a monotonically increasing function of temperature. This observation agrees with the results of Rogers and co-workers.
Volume 13 Issue 5 November 1979 pp 525-533 Quantum Mechanics
An ansatz is introduced in the Gordon’s method for nonlocal separable potentials to construct expressions for off-shell wave functions associated with the physical, regular and standing wave boundary conditions. This method has certain calculational advantages and is particularly suitable for dealing with potentials of higher rank. Results obtained for the Mongan case IV potential agree with those derived by the complicated techniques.
Volume 16 Issue 1 January 1981 pp 91-98 Quantum Mechanics
We derive an off-energy-shell generalization of the two-potential formula by using a coordinate-space approach and apply the formalism to construct algorithms for studying spatial behaviour of the fully off-shell
Volume 17 Issue 3 September 1981 pp 229-244 Quantum Mechanics
We derive a coordinate space approach to energy-dependent separable potentials and clearly demonstrate its calculational advantage. The results presented include expressions for (i) low-energy scattering parameters and (ii) off-energy-shell
Volume 28 Issue 4 April 1987 pp 325-334 Quantum Mechanics
Scattering formalisms which incorporate antisymmetrization of the projectile with respect to identical particles in the target result in a nonsymmetric non-local interaction. Such an interaction constraints the relative wavefunctions to be orthogonal to redundant states forbidden by the Pauli principle. Concentrating on the nonsymmetric non-local kernel of Saito we try to visualize the mechanisms by which a potential can ensure the required orthogonality. We achieve this by replacing the Saito kernel by an effective symmetric non-local potential. The constructed symmetric potential is found to be phase-equivalent only but not off-shell equivalent to the original kernel. This difference in the off-shell behaviour is attributed to the dynamical origin simulating the redundant states. In close analogy with one of our recent works we also derive an energy-momentum dependent equivalent to the local potential. Our solution of the pseudo inverse problem is exact and provides a basis for writing the phase—and quasiphase—equations. We present numerical results in support of this.
Volume 33 Issue 3 September 1989 pp 381-389 Nuclear Physics
We have adapted the phase-function method for studying on- and off-shell properties of velocity-dependent potentials. The main result presented in this paper is an ansatz for the interpolating
Volume 36 Issue 3 March 1991 pp 289-304
We construct a closed form expression for the off-shell Jost function for scattering by the Coulomb-distorted Graz separable potential and express it in the ‘maximal reduced form’. Our result is particularly suitable for numerical computation. We present a case study in support of this and examine the role of Coulomb interaction in the
Volume 39 Issue 5 November 1992 pp 501-508 Research Articles
We consider the scattering problem for absorptive interactions within the framework of phase-function method. A Green’s function approach is used to derive the phase equation. As a case study we apply the algorithm presented on a shallow α-α potential, the real and imaginary parts of which have been deduced from experimental data. The real and imaginary parts of the
Volume 45 Issue 6 December 1995 pp 499-509 Research Articles
A rigorous derivation of the optical theorem (OT) from the conservation of probability flux (CPF) is presented for scattering on an arbitrary spherically symmetric potential in
Volume 58 Issue 3 March 2002 pp 443-448 Research Articles
A base-equation method is implemented to realize the hereditary algebra of the Korteweg-de Vries (KdV) hierarchy and the
Volume 88 Issue 2 February 2017 Article ID 0028 Regular
We examine the effect of dissipation on travelling waves in nonlinear dispersive systems modelled by Benjamin–Bona–Mahony (BBM)-like equations. In the absence of dissipation, the BBM-like equations are found to support soliton and compacton/anticompacton solutions depending on whether the dispersive term islinear or nonlinear. We study the influence of increasing nonlinearity of the medium on the soliton and compacton dynamics. The dissipative effect is found to convert the solitons either to undular bores or to shock-like waves depending on the degree of nonlinearity of the equations. The anticompacton solutions are also transformed to undular bores by the effect of dissipation. But the compactons tend to vanish due to viscous effects. The local oscillatory structures behind the bores and/or shock-like waves in the case of solitons and anticompactons are found to depend sensitively both on the coefficient of viscosity and solution of the unperturbed problem.
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