Sambhu N Datta
Articles written in Pramana – Journal of Physics
Volume 18 Issue 2 February 1982 pp 113-120 Quantum Mechanics
Newtonian and fluid-dynamical viewpoint of pseudopotentials
A generalized time-dependent pseudopotential is defined. Analogue of the Newtonian equation is derived for stationary states and pseudoforces are physically interpreted. Physical points are also made from the analogous equation of continuity and the Euler equations.
Volume 20 Issue 1 January 1983 pp 104-104 Erratum
Volume 20 Issue 3 March 1983 pp 251-265 Quantum Mechanics
Fluid-dynamical representations of the Dirac equation
A relative kinetic mass operator is defined by
Volume 22 Issue 2 February 1984 pp 1- Letter
Pseudopotential is used as a formal operator to write the exact time-dependence of a pseudoexciton and hence that of an initial excitation spatially localized in a crystal. The exponential operator where pseudopotential occurs at the argument is readily evaluated using the property of projection operators. Migration of an initially localized excitation is of considerable experimental importance and can be of conceptual use since it should eventually generate the characteristics of a migrating exciton. From the formal time-dependence of a localized excitation, its spread with time can be calculated with relative ease. In a concurrent discussion, the previous work of Merrifield (1958) on the propagation of excitation is criticized and an error is pointed out. The spread, however, remains wavelike and is not dissipative in the absence of a collisional mechanism.
Volume 23 Issue 2 August 1984 pp 1- Letters
Conditions for the relativistic virial theorem for one electron
Conditions for the usual form of one-electron relativistic virial theorem to be satisfied are derived and illustrated. These can be applied to generate quality basic spinors for solving a one-electron Dirac equation.
Volume 23 Issue 4 October 1984 pp 467-473 Quantum Physics
Analysis and merit of the constrained-component variation in dirac theory
It is shown that the constrained-component variation generally suggested by Rosicky and Mark is very fundamental, has consistent variational features and reproduces, as a special case, earlier variational results for atomic systems obtained by Drake and Goldman. Numerical merits and demerits of this method are qualitatively assessed.
Volume 41 Issue 4 October 1993 pp 345-362
A set of indigenously developed computer programs for ab-initio Hartree-Fock calculations on both closed- and open-shell molecules have been described. These programs have been written for calculations using GTO basis sets. Integral formulae have been taken from Taketa
Volume 41 Issue 4 October 1993 pp 363-370
Computer programs for
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